Lots of refactoring, add tps command

28 files changed, 2486 insertions, 163 deletions

diff --git a/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java b/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java
index ef21d1c..8eb4565 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java
@@ -21,19 +21,20 @@
 package me.lucko.spark.common;
 
 import com.google.common.collect.ImmutableList;
-
 import me.lucko.spark.common.command.Arguments;
 import me.lucko.spark.common.command.Command;
+import me.lucko.spark.common.command.CommandResponseHandler;
 import me.lucko.spark.common.command.modules.MemoryModule;
+import me.lucko.spark.common.command.modules.MonitoringModule;
 import me.lucko.spark.common.command.modules.SamplerModule;
 import me.lucko.spark.common.command.modules.TickMonitoringModule;
 import me.lucko.spark.common.command.tabcomplete.CompletionSupplier;
 import me.lucko.spark.common.command.tabcomplete.TabCompleter;
-import me.lucko.spark.sampler.ThreadDumper;
-import me.lucko.spark.sampler.TickCounter;
-import me.lucko.spark.util.BytebinClient;
+import me.lucko.spark.common.monitor.tick.TpsCalculator;
+import me.lucko.spark.common.sampler.TickCounter;
+import me.lucko.spark.common.util.BytebinClient;
+import okhttp3.OkHttpClient;
 
-import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -41,52 +42,68 @@ import java.util.List;
 import java.util.stream.Collectors;
 
 /**
- * Abstract command handling class used by all platforms.
+ * Abstract spark implementation used by all platforms.
  *
  * @param <S> the sender (e.g. CommandSender) type used by the platform
  */
-public abstract class SparkPlatform<S> {
+public class SparkPlatform<S> {
 
     /** The URL of the viewer frontend */
     public static final String VIEWER_URL = "https://sparkprofiler.github.io/#";
+    /** The shared okhttp client */
+    private static final OkHttpClient OK_HTTP_CLIENT = new OkHttpClient();
     /** The bytebin instance used by the platform */
-    public static final BytebinClient BYTEBIN_CLIENT = new BytebinClient("https://bytebin.lucko.me/", "spark-plugin");
-
-    /** The prefix used in all messages */
-    private static final String PREFIX = "&8[&fspark&8] &7";
-    
-    private static <T> List<Command<T>> prepareCommands() {
-        ImmutableList.Builder<Command<T>> builder = ImmutableList.builder();
-        new SamplerModule<T>().registerCommands(builder::add);
-        new TickMonitoringModule<T>().registerCommands(builder::add);
-        new MemoryModule<T>().registerCommands(builder::add);
-        return builder.build();
+    public static final BytebinClient BYTEBIN_CLIENT = new BytebinClient(OK_HTTP_CLIENT, "https://bytebin.lucko.me/", "spark-plugin");
+
+    private final List<Command<S>> commands;
+    private final SparkPlugin<S> plugin;
+
+    private final TickCounter tickCounter;
+    private final TpsCalculator tpsCalculator;
+
+    public SparkPlatform(SparkPlugin<S> plugin) {
+        this.plugin = plugin;
+
+        ImmutableList.Builder<Command<S>> commandsBuilder = ImmutableList.builder();
+        new SamplerModule<S>().registerCommands(commandsBuilder::add);
+        new MonitoringModule<S>().registerCommands(commandsBuilder::add);
+        new TickMonitoringModule<S>().registerCommands(commandsBuilder::add);
+        new MemoryModule<S>().registerCommands(commandsBuilder::add);
+        this.commands = commandsBuilder.build();
+
+        this.tickCounter = plugin.createTickCounter();
+        this.tpsCalculator = this.tickCounter != null ? new TpsCalculator() : null;
+    }
+
+    public void enable() {
+        if (this.tickCounter != null) {
+            this.tickCounter.addTickTask(this.tpsCalculator);
+            this.tickCounter.start();
+        }
+    }
+
+    public void disable() {
+        if (this.tickCounter != null) {
+            this.tickCounter.close();
+        }
+    }
+
+    public SparkPlugin<S> getPlugin() {
+        return this.plugin;
     }
 
-    private final List<Command<S>> commands = prepareCommands();
-    
-    // abstract methods implemented by each platform
-    public abstract String getVersion();
-    public abstract Path getPluginFolder();
-    public abstract String getLabel();
-    public abstract void sendMessage(S sender, String message);
-    public abstract void sendMessage(String message);
-    public abstract void sendLink(String url);
-    public abstract void runAsync(Runnable r);
-    public abstract ThreadDumper getDefaultThreadDumper();
-    public abstract TickCounter newTickCounter();
-
-    public void sendPrefixedMessage(S sender, String message) {
-        sendMessage(sender, PREFIX + message);
+    public TickCounter getTickCounter() {
+        return this.tickCounter;
     }
 
-    public void sendPrefixedMessage(String message) {
-        sendMessage(PREFIX + message);
+    public TpsCalculator getTpsCalculator() {
+        return this.tpsCalculator;
     }
 
     public void executeCommand(S sender, String[] args) {
+        CommandResponseHandler<S> resp = new CommandResponseHandler<>(this, sender);
         if (args.length == 0) {
-            sendUsage(sender);
+            sendUsage(resp);
             return;
         }
 
@@ -96,15 +113,15 @@ public abstract class SparkPlatform<S> {
         for (Command<S> command : this.commands) {
             if (command.aliases().contains(alias)) {
                 try {
-                    command.executor().execute(this, sender, new Arguments(rawArgs));
+                    command.executor().execute(this, sender, resp, new Arguments(rawArgs));
                 } catch (IllegalArgumentException e) {
-                    sendMessage(sender, "&c" + e.getMessage());
+                    resp.replyPrefixed("&c" + e.getMessage());
                 }
                 return;
             }
         }
 
-        sendUsage(sender);
+        sendUsage(resp);
     }
 
     public List<String> tabCompleteCommand(S sender, String[] args) {
@@ -127,15 +144,15 @@ public abstract class SparkPlatform<S> {
         return Collections.emptyList();
     }
 
-    private void sendUsage(S sender) {
-        sendPrefixedMessage(sender, "&fspark &7v" + getVersion());
+    private void sendUsage(CommandResponseHandler<S> sender) {
+        sender.replyPrefixed("&fspark &7v" + getPlugin().getVersion());
         for (Command<S> command : this.commands) {
-            sendMessage(sender, "&b&l> &7/" + getLabel() + " " + command.aliases().get(0));
+            sender.reply("&b&l> &7/" + getPlugin().getLabel() + " " + command.aliases().get(0));
             for (Command.ArgumentInfo arg : command.arguments()) {
                 if (arg.requiresParameter()) {
-                    sendMessage(sender, "       &8[&7--" + arg.argumentName() + "&8 <" + arg.parameterDescription() + ">]");
+                    sender.reply("       &8[&7--" + arg.argumentName() + "&8 <" + arg.parameterDescription() + ">]");
                 } else {
-                    sendMessage(sender, "       &8[&7--" + arg.argumentName() + "]");
+                    sender.reply("       &8[&7--" + arg.argumentName() + "]");
                 }
             }
         }
diff --git a/spark-common/src/main/java/me/lucko/spark/common/SparkPlugin.java b/spark-common/src/main/java/me/lucko/spark/common/SparkPlugin.java
new file mode 100644
index 0000000..7a3a353
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/SparkPlugin.java
@@ -0,0 +1,49 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common;
+
+import me.lucko.spark.common.sampler.ThreadDumper;
+import me.lucko.spark.common.sampler.TickCounter;
+
+import java.nio.file.Path;
+import java.util.Set;
+
+public interface SparkPlugin<S> {
+
+    String getVersion();
+
+    Path getPluginFolder();
+
+    String getLabel();
+
+    Set<S> getSenders();
+
+    void sendMessage(S sender, String message);
+
+    void sendLink(S sender, String url);
+
+    void runAsync(Runnable r);
+
+    ThreadDumper getDefaultThreadDumper();
+
+    TickCounter createTickCounter();
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/command/Command.java b/spark-common/src/main/java/me/lucko/spark/common/command/Command.java
index fb440b1..c9f6551 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/command/Command.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/command/Command.java
@@ -21,7 +21,6 @@
 package me.lucko.spark.common.command;
 
 import com.google.common.collect.ImmutableList;
-
 import me.lucko.spark.common.SparkPlatform;
 
 import java.util.Collections;
@@ -109,7 +108,7 @@ public class Command<S> {
 
     @FunctionalInterface
     public interface Executor<S> {
-        void execute(SparkPlatform<S> platform, S sender, Arguments arguments);
+        void execute(SparkPlatform<S> platform, S sender, CommandResponseHandler resp, Arguments arguments);
     }
 
     @FunctionalInterface
diff --git a/spark-common/src/main/java/me/lucko/spark/common/command/CommandResponseHandler.java b/spark-common/src/main/java/me/lucko/spark/common/command/CommandResponseHandler.java
new file mode 100644
index 0000000..a5a7391
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/command/CommandResponseHandler.java
@@ -0,0 +1,75 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.command;
+
+import me.lucko.spark.common.SparkPlatform;
+
+import java.util.Set;
+import java.util.function.Consumer;
+
+public class CommandResponseHandler<S> {
+
+    /** The prefix used in all messages */
+    private static final String PREFIX = "&8[&fspark&8] &7";
+
+    private final SparkPlatform<S> platform;
+    private final S sender;
+
+    public CommandResponseHandler(SparkPlatform<S> platform, S sender) {
+        this.platform = platform;
+        this.sender = sender;
+    }
+
+    public S sender() {
+        return this.sender;
+    }
+
+    public void allSenders(Consumer<? super S> action) {
+        Set<S> senders = this.platform.getPlugin().getSenders();
+        senders.add(this.sender);
+        senders.forEach(action);
+    }
+
+    public void reply(String message) {
+        this.platform.getPlugin().sendMessage(this.sender, message);
+    }
+
+    public void broadcast(String message) {
+        allSenders(sender -> this.platform.getPlugin().sendMessage(sender, message));
+    }
+
+    public void replyPrefixed(String message) {
+        this.platform.getPlugin().sendMessage(this.sender, PREFIX + message);
+    }
+
+    public void broadcastPrefixed(String message) {
+        allSenders(sender -> this.platform.getPlugin().sendMessage(sender, PREFIX + message));
+    }
+
+    public void replyLink(String link) {
+        this.platform.getPlugin().sendLink(this.sender, link);
+    }
+
+    public void broadcastLink(String link) {
+        allSenders(sender -> this.platform.getPlugin().sendLink(sender, link));
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/command/modules/MemoryModule.java b/spark-common/src/main/java/me/lucko/spark/common/command/modules/MemoryModule.java
index 5f17d54..2cb2e07 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/command/modules/MemoryModule.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/command/modules/MemoryModule.java
@@ -24,9 +24,8 @@ import me.lucko.spark.common.SparkPlatform;
 import me.lucko.spark.common.command.Command;
 import me.lucko.spark.common.command.CommandModule;
 import me.lucko.spark.common.command.tabcomplete.TabCompleter;
-import me.lucko.spark.memory.HeapDump;
-import me.lucko.spark.memory.HeapDumpSummary;
-
+import me.lucko.spark.common.memory.HeapDump;
+import me.lucko.spark.common.memory.HeapDumpSummary;
 import okhttp3.MediaType;
 
 import java.io.IOException;
@@ -44,34 +43,34 @@ public class MemoryModule<S> implements CommandModule<S> {
         consumer.accept(Command.<S>builder()
                 .aliases("heapsummary")
                 .argumentUsage("run-gc-before", null)
-                .executor((platform, sender, arguments) -> {
-                    platform.runAsync(() -> {
-                        if (arguments.boolFlag("run-gc-before")) {
-                            platform.sendPrefixedMessage("&7Running garbage collector...");
-                            System.gc();
-                        }
-
-                        platform.sendPrefixedMessage("&7Creating a new heap dump summary, please wait...");
-
-                        HeapDumpSummary heapDump;
-                        try {
-                            heapDump = HeapDumpSummary.createNew();
-                        } catch (Exception e) {
-                            platform.sendPrefixedMessage("&cAn error occurred whilst inspecting the heap.");
-                            e.printStackTrace();
-                            return;
-                        }
-
-                        byte[] output = heapDump.formCompressedDataPayload();
-                        try {
-                            String key = SparkPlatform.BYTEBIN_CLIENT.postGzippedContent(output, JSON_TYPE);
-                            platform.sendPrefixedMessage("&bHeap dump summmary output:");
-                            platform.sendLink(SparkPlatform.VIEWER_URL + key);
-                        } catch (IOException e) {
-                            platform.sendPrefixedMessage("&cAn error occurred whilst uploading the data.");
-                            e.printStackTrace();
-                        }
-                    });
+                .executor((platform, sender, resp, arguments) -> {
+                    platform.getPlugin().runAsync(() -> {
+                                    if (arguments.boolFlag("run-gc-before")) {
+                                        resp.broadcastPrefixed("&7Running garbage collector...");
+                                        System.gc();
+                                    }
+
+                                    resp.broadcastPrefixed("&7Creating a new heap dump summary, please wait...");
+
+                                    HeapDumpSummary heapDump;
+                                    try {
+                                        heapDump = HeapDumpSummary.createNew();
+                                    } catch (Exception e) {
+                                        resp.broadcastPrefixed("&cAn error occurred whilst inspecting the heap.");
+                                        e.printStackTrace();
+                                        return;
+                                    }
+
+                                    byte[] output = heapDump.formCompressedDataPayload();
+                                    try {
+                                        String key = SparkPlatform.BYTEBIN_CLIENT.postContent(output, JSON_TYPE, false).key();
+                                        resp.broadcastPrefixed("&bHeap dump summmary output:");
+                                        resp.broadcastLink(SparkPlatform.VIEWER_URL + key);
+                                    } catch (IOException e) {
+                                        resp.broadcastPrefixed("&cAn error occurred whilst uploading the data.");
+                                        e.printStackTrace();
+                                    }
+                                });
                 })
                 .tabCompleter((platform, sender, arguments) -> TabCompleter.completeForOpts(arguments, "--run-gc-before"))
                 .build()
@@ -81,35 +80,36 @@ public class MemoryModule<S> implements CommandModule<S> {
                 .aliases("heapdump")
                 .argumentUsage("run-gc-before", null)
                 .argumentUsage("include-non-live", null)
-                .executor((platform, sender, arguments) -> {
-                    platform.runAsync(() -> {
-                        Path pluginFolder = platform.getPluginFolder();
-                        try {
-                            Files.createDirectories(pluginFolder);
-                        } catch (IOException e) {
-                            // ignore
-                        }
-
-                        Path file = pluginFolder.resolve("heap-" + DateTimeFormatter.ofPattern("yyyy-MM-dd_HH.mm.ss").format(LocalDateTime.now()) + (HeapDump.isOpenJ9() ? ".phd" : ".hprof"));
-                        boolean liveOnly = !arguments.boolFlag("include-non-live");
-
-                        if (arguments.boolFlag("run-gc-before")) {
-                            platform.sendPrefixedMessage("&7Running garbage collector...");
-                            System.gc();
-                        }
-
-                        platform.sendPrefixedMessage("&7Creating a new heap dump, please wait...");
-
-                        try {
-                            HeapDump.dumpHeap(file, liveOnly);
-                        } catch (Exception e) {
-                            platform.sendPrefixedMessage("&cAn error occurred whilst creating a heap dump.");
-                            e.printStackTrace();
-                            return;
-                        }
-
-                        platform.sendPrefixedMessage("&bHeap dump written to: " + file.toString());
-                    });
+                .executor((platform, sender, resp, arguments) -> {
+                    // ignore
+                    platform.getPlugin().runAsync(() -> {
+                                    Path pluginFolder = platform.getPlugin().getPluginFolder();
+                                    try {
+                                        Files.createDirectories(pluginFolder);
+                                    } catch (IOException e) {
+                                        // ignore
+                                    }
+
+                                    Path file = pluginFolder.resolve("heap-" + DateTimeFormatter.ofPattern("yyyy-MM-dd_HH.mm.ss").format(LocalDateTime.now()) + (HeapDump.isOpenJ9() ? ".phd" : ".hprof"));
+                                    boolean liveOnly = !arguments.boolFlag("include-non-live");
+
+                                    if (arguments.boolFlag("run-gc-before")) {
+                                        resp.broadcastPrefixed("&7Running garbage collector...");
+                                        System.gc();
+                                    }
+
+                                    resp.broadcastPrefixed("&7Creating a new heap dump, please wait...");
+
+                                    try {
+                                        HeapDump.dumpHeap(file, liveOnly);
+                                    } catch (Exception e) {
+                                        resp.broadcastPrefixed("&cAn error occurred whilst creating a heap dump.");
+                                        e.printStackTrace();
+                                        return;
+                                    }
+
+                                    resp.broadcastPrefixed("&bHeap dump written to: " + file.toString());
+                                });
                 })
                 .tabCompleter((platform, sender, arguments) -> TabCompleter.completeForOpts(arguments, "--run-gc-before", "--include-non-live"))
                 .build()
diff --git a/spark-common/src/main/java/me/lucko/spark/common/command/modules/MonitoringModule.java b/spark-common/src/main/java/me/lucko/spark/common/command/modules/MonitoringModule.java
new file mode 100644
index 0000000..b543e1d
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/command/modules/MonitoringModule.java
@@ -0,0 +1,51 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.command.modules;
+
+import me.lucko.spark.common.command.Command;
+import me.lucko.spark.common.command.CommandModule;
+import me.lucko.spark.common.monitor.tick.TpsCalculator;
+
+import java.util.function.Consumer;
+
+public class MonitoringModule<S> implements CommandModule<S> {
+
+    @Override
+    public void registerCommands(Consumer<Command<S>> consumer) {
+        consumer.accept(Command.<S>builder()
+                .aliases("tps")
+                .executor((platform, sender, resp, arguments) -> {
+                    TpsCalculator tpsCalculator = platform.getTpsCalculator();
+                    if (tpsCalculator == null) {
+                        resp.replyPrefixed("TPS data is not available.");
+                        return;
+                    }
+
+                    String formattedTpsString = tpsCalculator.toFormattedString();
+                    resp.replyPrefixed("TPS from last 5s, 10s, 1m, 5m, 15m");
+                    resp.replyPrefixed(formattedTpsString);
+                })
+                .tabCompleter(Command.TabCompleter.empty())
+                .build()
+        );
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/command/modules/SamplerModule.java b/spark-common/src/main/java/me/lucko/spark/common/command/modules/SamplerModule.java
index 9d00a96..a0f171c 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/command/modules/SamplerModule.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/command/modules/SamplerModule.java
@@ -23,14 +23,14 @@ package me.lucko.spark.common.command.modules;
 import me.lucko.spark.common.SparkPlatform;
 import me.lucko.spark.common.command.Command;
 import me.lucko.spark.common.command.CommandModule;
+import me.lucko.spark.common.command.CommandResponseHandler;
 import me.lucko.spark.common.command.tabcomplete.CompletionSupplier;
 import me.lucko.spark.common.command.tabcomplete.TabCompleter;
-import me.lucko.spark.sampler.Sampler;
-import me.lucko.spark.sampler.SamplerBuilder;
-import me.lucko.spark.sampler.ThreadDumper;
-import me.lucko.spark.sampler.ThreadGrouper;
-import me.lucko.spark.sampler.TickCounter;
-
+import me.lucko.spark.common.sampler.Sampler;
+import me.lucko.spark.common.sampler.SamplerBuilder;
+import me.lucko.spark.common.sampler.ThreadDumper;
+import me.lucko.spark.common.sampler.ThreadGrouper;
+import me.lucko.spark.common.sampler.TickCounter;
 import okhttp3.MediaType;
 
 import java.io.IOException;
@@ -62,15 +62,15 @@ public class SamplerModule<S> implements CommandModule<S> {
                 .argumentUsage("interval", "interval millis")
                 .argumentUsage("only-ticks-over", "tick length millis")
                 .argumentUsage("include-line-numbers", null)
-                .executor((platform, sender, arguments) -> {
+                .executor((platform, sender, resp, arguments) -> {
                     int timeoutSeconds = arguments.intFlag("timeout");
                     if (timeoutSeconds != -1 && timeoutSeconds <= 10) {
-                        platform.sendPrefixedMessage(sender, "&cThe specified timeout is not long enough for accurate results to be formed. Please choose a value greater than 10.");
+                        resp.replyPrefixed("&cThe specified timeout is not long enough for accurate results to be formed. Please choose a value greater than 10.");
                         return;
                     }
 
                     if (timeoutSeconds != -1 && timeoutSeconds < 30) {
-                        platform.sendPrefixedMessage(sender, "&7The accuracy of the output will significantly improve when sampling is able to run for longer periods. Consider setting a timeout value over 30 seconds.");
+                        resp.replyPrefixed("&7The accuracy of the output will significantly improve when sampling is able to run for longer periods. Consider setting a timeout value over 30 seconds.");
                     }
 
                     double intervalMillis = arguments.doubleFlag("interval");
@@ -84,7 +84,7 @@ public class SamplerModule<S> implements CommandModule<S> {
                     ThreadDumper threadDumper;
                     if (threads.isEmpty()) {
                         // use the server thread
-                        threadDumper = platform.getDefaultThreadDumper();
+                        threadDumper = platform.getPlugin().getDefaultThreadDumper();
                     } else if (threads.contains("*")) {
                         threadDumper = ThreadDumper.ALL;
                     } else {
@@ -108,10 +108,9 @@ public class SamplerModule<S> implements CommandModule<S> {
                     int ticksOver = arguments.intFlag("only-ticks-over");
                     TickCounter tickCounter = null;
                     if (ticksOver != -1) {
-                        try {
-                            tickCounter = platform.newTickCounter();
-                        } catch (UnsupportedOperationException e) {
-                            platform.sendPrefixedMessage(sender, "&cTick counting is not supported!");
+                        tickCounter = platform.getTickCounter();
+                        if (tickCounter == null) {
+                            resp.replyPrefixed("&cTick counting is not supported!");
                             return;
                         }
                     }
@@ -119,11 +118,11 @@ public class SamplerModule<S> implements CommandModule<S> {
                     Sampler sampler;
                     synchronized (this.activeSamplerMutex) {
                         if (this.activeSampler != null) {
-                            platform.sendPrefixedMessage(sender, "&7An active sampler is already running.");
+                            resp.replyPrefixed("&7An active sampler is already running.");
                             return;
                         }
 
-                        platform.sendPrefixedMessage("&7Initializing a new profiler, please wait...");
+                        resp.broadcastPrefixed("&7Initializing a new profiler, please wait...");
 
                         SamplerBuilder builder = new SamplerBuilder();
                         builder.threadDumper(threadDumper);
@@ -138,11 +137,11 @@ public class SamplerModule<S> implements CommandModule<S> {
                         }
                         sampler = this.activeSampler = builder.start();
 
-                        platform.sendPrefixedMessage("&bProfiler now active!");
+                        resp.broadcastPrefixed("&bProfiler now active!");
                         if (timeoutSeconds == -1) {
-                            platform.sendPrefixedMessage("&7Use '/" + platform.getLabel() + " stop' to stop profiling and upload the results.");
+                            resp.broadcastPrefixed("&7Use '/" + platform.getPlugin().getLabel() + " stop' to stop profiling and upload the results.");
                         } else {
-                            platform.sendPrefixedMessage("&7The results will be automatically returned after the profiler has been running for " + timeoutSeconds + " seconds.");
+                            resp.broadcastPrefixed("&7The results will be automatically returned after the profiler has been running for " + timeoutSeconds + " seconds.");
                         }
                     }
 
@@ -151,7 +150,7 @@ public class SamplerModule<S> implements CommandModule<S> {
                     // send message if profiling fails
                     future.whenCompleteAsync((s, throwable) -> {
                         if (throwable != null) {
-                            platform.sendPrefixedMessage("&cSampling operation failed unexpectedly. Error: " + throwable.toString());
+                            resp.broadcastPrefixed("&cSampling operation failed unexpectedly. Error: " + throwable.toString());
                             throwable.printStackTrace();
                         }
                     });
@@ -168,8 +167,8 @@ public class SamplerModule<S> implements CommandModule<S> {
                     // await the result
                     if (timeoutSeconds != -1) {
                         future.thenAcceptAsync(s -> {
-                            platform.sendPrefixedMessage("&7The active sampling operation has completed! Uploading results...");
-                            handleUpload(platform, s);
+                            resp.broadcastPrefixed("&7The active sampling operation has completed! Uploading results...");
+                            handleUpload(platform, resp, s);
                         });
                     }
                 })
@@ -188,21 +187,21 @@ public class SamplerModule<S> implements CommandModule<S> {
 
         consumer.accept(Command.<S>builder()
                 .aliases("info")
-                .executor((platform, sender, arguments) -> {
+                .executor((platform, sender, resp, arguments) -> {
                     synchronized (this.activeSamplerMutex) {
                         if (this.activeSampler == null) {
-                            platform.sendPrefixedMessage(sender, "&7There isn't an active sampling task running.");
+                            resp.replyPrefixed("&7There isn't an active sampling task running.");
                         } else {
                             long timeout = this.activeSampler.getEndTime();
                             if (timeout == -1) {
-                                platform.sendPrefixedMessage(sender, "&7There is an active sampler currently running, with no defined timeout.");
+                                resp.replyPrefixed("&7There is an active sampler currently running, with no defined timeout.");
                             } else {
                                 long timeoutDiff = (timeout - System.currentTimeMillis()) / 1000L;
-                                platform.sendPrefixedMessage(sender, "&7There is an active sampler currently running, due to timeout in " + timeoutDiff + " seconds.");
+                                resp.replyPrefixed("&7There is an active sampler currently running, due to timeout in " + timeoutDiff + " seconds.");
                             }
 
                             long runningTime = (System.currentTimeMillis() - this.activeSampler.getStartTime()) / 1000L;
-                            platform.sendPrefixedMessage(sender, "&7It has been sampling for " + runningTime + " seconds so far.");
+                            resp.replyPrefixed("&7It has been sampling for " + runningTime + " seconds so far.");
                         }
                     }
                 })
@@ -211,14 +210,14 @@ public class SamplerModule<S> implements CommandModule<S> {
 
         consumer.accept(Command.<S>builder()
                 .aliases("stop", "upload", "paste")
-                .executor((platform, sender, arguments) -> {
+                .executor((platform, sender, resp, arguments) -> {
                     synchronized (this.activeSamplerMutex) {
                         if (this.activeSampler == null) {
-                            platform.sendPrefixedMessage(sender, "&7There isn't an active sampling task running.");
+                            resp.replyPrefixed("&7There isn't an active sampling task running.");
                         } else {
                             this.activeSampler.cancel();
-                            platform.sendPrefixedMessage("&7The active sampling operation has been stopped! Uploading results...");
-                            handleUpload(platform, this.activeSampler);
+                            resp.broadcastPrefixed("&7The active sampling operation has been stopped! Uploading results...");
+                            handleUpload(platform, resp, this.activeSampler);
                             this.activeSampler = null;
                         }
                     }
@@ -228,14 +227,14 @@ public class SamplerModule<S> implements CommandModule<S> {
 
         consumer.accept(Command.<S>builder()
                 .aliases("cancel")
-                .executor((platform, sender, arguments) -> {
+                .executor((platform, sender, resp, arguments) -> {
                     synchronized (this.activeSamplerMutex) {
                         if (this.activeSampler == null) {
-                            platform.sendPrefixedMessage(sender, "&7There isn't an active sampling task running.");
+                            resp.replyPrefixed("&7There isn't an active sampling task running.");
                         } else {
                             this.activeSampler.cancel();
                             this.activeSampler = null;
-                            platform.sendPrefixedMessage("&bThe active sampling task has been cancelled.");
+                            resp.broadcastPrefixed("&bThe active sampling task has been cancelled.");
                         }
                     }
                 })
@@ -243,15 +242,15 @@ public class SamplerModule<S> implements CommandModule<S> {
         );
     }
 
-    private void handleUpload(SparkPlatform<S> platform, Sampler sampler) {
-        platform.runAsync(() -> {
+    private void handleUpload(SparkPlatform<S> platform, CommandResponseHandler<S> resp, Sampler sampler) {
+        platform.getPlugin().runAsync(() -> {
             byte[] output = sampler.formCompressedDataPayload();
             try {
-                String key = SparkPlatform.BYTEBIN_CLIENT.postGzippedContent(output, JSON_TYPE);
-                platform.sendPrefixedMessage("&bSampling results:");
-                platform.sendLink(SparkPlatform.VIEWER_URL + key);
+                String key = SparkPlatform.BYTEBIN_CLIENT.postContent(output, JSON_TYPE, false).key();
+                resp.broadcastPrefixed("&bSampling results:");
+                resp.broadcastLink(SparkPlatform.VIEWER_URL + key);
             } catch (IOException e) {
-                platform.sendPrefixedMessage("&cAn error occurred whilst uploading the results.");
+                resp.broadcastPrefixed("&cAn error occurred whilst uploading the results.");
                 e.printStackTrace();
             }
         });
diff --git a/spark-common/src/main/java/me/lucko/spark/common/command/modules/TickMonitoringModule.java b/spark-common/src/main/java/me/lucko/spark/common/command/modules/TickMonitoringModule.java
index 3ad8909..bea7a07 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/command/modules/TickMonitoringModule.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/command/modules/TickMonitoringModule.java
@@ -20,12 +20,12 @@
 
 package me.lucko.spark.common.command.modules;
 
-import me.lucko.spark.common.SparkPlatform;
 import me.lucko.spark.common.command.Command;
 import me.lucko.spark.common.command.CommandModule;
+import me.lucko.spark.common.command.CommandResponseHandler;
 import me.lucko.spark.common.command.tabcomplete.TabCompleter;
-import me.lucko.spark.monitor.TickMonitor;
-import me.lucko.spark.sampler.TickCounter;
+import me.lucko.spark.common.monitor.tick.TickMonitor;
+import me.lucko.spark.common.sampler.TickCounter;
 
 import java.util.function.Consumer;
 
@@ -37,27 +37,29 @@ public class TickMonitoringModule<S> implements CommandModule<S> {
     @Override
     public void registerCommands(Consumer<Command<S>> consumer) {
         consumer.accept(Command.<S>builder()
-                .aliases("monitoring")
+                .aliases("tickmonitoring")
                 .argumentUsage("threshold", "percentage increase")
                 .argumentUsage("without-gc", null)
-                .executor((platform, sender, arguments) -> {
-                    if (this.activeTickMonitor == null) {
+                .executor((platform, sender, resp, arguments) -> {
+                    TickCounter tickCounter = platform.getTickCounter();
+                    if (tickCounter == null) {
+                        resp.replyPrefixed("&cNot supported!");
+                        return;
+                    }
 
+                    if (this.activeTickMonitor == null) {
                         int threshold = arguments.intFlag("threshold");
                         if (threshold == -1) {
                             threshold = 100;
                         }
 
-                        try {
-                            TickCounter tickCounter = platform.newTickCounter();
-                            this.activeTickMonitor = new ReportingTickMonitor(platform, tickCounter, threshold, !arguments.boolFlag("without-gc"));
-                        } catch (UnsupportedOperationException e) {
-                            platform.sendPrefixedMessage(sender, "&cNot supported!");
-                        }
+                        this.activeTickMonitor = new ReportingTickMonitor(resp, tickCounter, threshold, !arguments.boolFlag("without-gc"));
+                        tickCounter.addTickTask(this.activeTickMonitor);
                     } else {
+                        tickCounter.removeTickTask(this.activeTickMonitor);
                         this.activeTickMonitor.close();
                         this.activeTickMonitor = null;
-                        platform.sendPrefixedMessage("&7Tick monitor disabled.");
+                        resp.broadcastPrefixed("&7Tick monitor disabled.");
                     }
                 })
                 .tabCompleter((platform, sender, arguments) -> TabCompleter.completeForOpts(arguments, "--threshold", "--without-gc"))
@@ -66,16 +68,16 @@ public class TickMonitoringModule<S> implements CommandModule<S> {
     }
 
     private class ReportingTickMonitor extends TickMonitor {
-        private final SparkPlatform<S> platform;
+        private final CommandResponseHandler<S> resp;
 
-        ReportingTickMonitor(SparkPlatform<S> platform, TickCounter tickCounter, int percentageChangeThreshold, boolean monitorGc) {
+        ReportingTickMonitor(CommandResponseHandler<S> resp, TickCounter tickCounter, int percentageChangeThreshold, boolean monitorGc) {
             super(tickCounter, percentageChangeThreshold, monitorGc);
-            this.platform = platform;
+            this.resp = resp;
         }
 
         @Override
         protected void sendMessage(String message) {
-            this.platform.sendPrefixedMessage(message);
+            this.resp.broadcastPrefixed(message);
         }
     }
 }
diff --git a/spark-common/src/main/java/me/lucko/spark/common/memory/HeapDump.java b/spark-common/src/main/java/me/lucko/spark/common/memory/HeapDump.java
new file mode 100644
index 0000000..6200c17
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/memory/HeapDump.java
@@ -0,0 +1,77 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.memory;
+
+import javax.management.JMX;
+import javax.management.MBeanServer;
+import javax.management.ObjectName;
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.lang.reflect.Method;
+import java.nio.file.Path;
+
+/**
+ * Utility for creating .hprof memory heap snapshots.
+ */
+public final class HeapDump {
+
+    private HeapDump() {}
+
+    /** The object name of the com.sun.management.HotSpotDiagnosticMXBean */
+    private static final String DIAGNOSTIC_BEAN = "com.sun.management:type=HotSpotDiagnostic";
+
+    /**
+     * Creates a heap dump at the given output path.
+     *
+     * @param outputPath the path to write the snapshot to
+     * @param live if true dump only live objects i.e. objects that are reachable from others
+     * @throws Exception catch all
+     */
+    public static void dumpHeap(Path outputPath, boolean live) throws Exception {
+        String outputPathString = outputPath.toAbsolutePath().normalize().toString();
+
+        if (isOpenJ9()) {
+            Class<?> dumpClass = Class.forName("com.ibm.jvm.Dump");
+            Method heapDumpMethod = dumpClass.getMethod("heapDumpToFile", String.class);
+            heapDumpMethod.invoke(null, outputPathString);
+        } else {
+            MBeanServer beanServer = ManagementFactory.getPlatformMBeanServer();
+            ObjectName diagnosticBeanName = ObjectName.getInstance(DIAGNOSTIC_BEAN);
+
+            HotSpotDiagnosticMXBean proxy = JMX.newMXBeanProxy(beanServer, diagnosticBeanName, HotSpotDiagnosticMXBean.class);
+            proxy.dumpHeap(outputPathString, live);
+        }
+    }
+
+    public static boolean isOpenJ9() {
+        try {
+            Class.forName("com.ibm.jvm.Dump");
+            return true;
+        } catch (ClassNotFoundException e) {
+            return false;
+        }
+    }
+
+    public interface HotSpotDiagnosticMXBean {
+        void dumpHeap(String outputFile, boolean live) throws IOException;
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/memory/HeapDumpSummary.java b/spark-common/src/main/java/me/lucko/spark/common/memory/HeapDumpSummary.java
new file mode 100644
index 0000000..f3f62db
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/memory/HeapDumpSummary.java
@@ -0,0 +1,171 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.memory;
+
+import com.google.gson.stream.JsonWriter;
+import me.lucko.spark.common.util.TypeDescriptors;
+
+import javax.management.JMX;
+import javax.management.MBeanServer;
+import javax.management.ObjectName;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.lang.management.ManagementFactory;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+import java.util.zip.GZIPOutputStream;
+
+/**
+ * Represents a "heap dump summary" from the VM.
+ *
+ * <p>Contains a number of entries, corresponding to types of objects in the virtual machine
+ * and their recorded impact on memory usage.</p>
+ */
+public final class HeapDumpSummary {
+
+    /** The object name of the com.sun.management.DiagnosticCommandMBean */
+    private static final String DIAGNOSTIC_BEAN = "com.sun.management:type=DiagnosticCommand";
+    /** A regex pattern representing the expected format of the raw heap output */
+    private static final Pattern OUTPUT_FORMAT = Pattern.compile("^\\s*(\\d+):\\s*(\\d+)\\s*(\\d+)\\s*([^\\s]+).*$");
+
+    /**
+     * Obtains the raw heap data output from the DiagnosticCommandMBean.
+     *
+     * @return the raw output
+     * @throws Exception lots could go wrong!
+     */
+    private static String getRawHeapData() throws Exception {
+        MBeanServer beanServer = ManagementFactory.getPlatformMBeanServer();
+        ObjectName diagnosticBeanName = ObjectName.getInstance(DIAGNOSTIC_BEAN);
+
+        DiagnosticCommandMXBean proxy = JMX.newMXBeanProxy(beanServer, diagnosticBeanName, DiagnosticCommandMXBean.class);
+        return proxy.gcClassHistogram(new String[0]);
+    }
+
+    /**
+     * Creates a new heap dump based on the current VM.
+     *
+     * @return the created heap dump
+     * @throws RuntimeException if an error occurred whilst requesting a heap dump from the VM
+     */
+    public static HeapDumpSummary createNew() {
+        String rawOutput;
+        try {
+            rawOutput = getRawHeapData();
+        } catch (Exception e) {
+            throw new RuntimeException("Unable to get heap dump", e);
+        }
+
+        return new HeapDumpSummary(Arrays.stream(rawOutput.split("\n"))
+                .map(line -> {
+                    Matcher matcher = OUTPUT_FORMAT.matcher(line);
+                    if (!matcher.matches()) {
+                        return null;
+                    }
+
+                    return new Entry(
+                            Integer.parseInt(matcher.group(1)),
+                            Integer.parseInt(matcher.group(2)),
+                            Long.parseLong(matcher.group(3)),
+                            TypeDescriptors.getJavaType(matcher.group(4))
+                    );
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toList()));
+    }
+
+    /** The entries in this heap dump */
+    private final List<Entry> entries;
+
+    private HeapDumpSummary(List<Entry> entries) {
+        this.entries = entries;
+    }
+
+    private void writeOutput(JsonWriter writer) throws IOException {
+        writer.beginObject();
+        writer.name("type").value("heap");
+        writer.name("entries").beginArray();
+        for (Entry entry : this.entries) {
+            writer.beginObject();
+            writer.name("#").value(entry.getOrder());
+            writer.name("i").value(entry.getInstances());
+            writer.name("s").value(entry.getBytes());
+            writer.name("t").value(entry.getType());
+            writer.endObject();
+        }
+        writer.endArray();
+        writer.endObject();
+    }
+
+    public byte[] formCompressedDataPayload() {
+        ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
+        try (Writer writer = new OutputStreamWriter(new GZIPOutputStream(byteOut), StandardCharsets.UTF_8)) {
+            try (JsonWriter jsonWriter = new JsonWriter(writer)) {
+                writeOutput(jsonWriter);
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+        return byteOut.toByteArray();
+    }
+
+    public static final class Entry {
+        private final int order;
+        private final int instances;
+        private final long bytes;
+        private final String type;
+
+        Entry(int order, int instances, long bytes, String type) {
+            this.order = order;
+            this.instances = instances;
+            this.bytes = bytes;
+            this.type = type;
+        }
+
+        public int getOrder() {
+            return this.order;
+        }
+
+        public int getInstances() {
+            return this.instances;
+        }
+
+        public long getBytes() {
+            return this.bytes;
+        }
+
+        public String getType() {
+            return this.type;
+        }
+    }
+
+    public interface DiagnosticCommandMXBean {
+        String gcClassHistogram(String[] args);
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/monitor/gc/GarbageCollectionMonitor.java b/spark-common/src/main/java/me/lucko/spark/common/monitor/gc/GarbageCollectionMonitor.java
new file mode 100644
index 0000000..93a5fd8
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/monitor/gc/GarbageCollectionMonitor.java
@@ -0,0 +1,90 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.monitor.gc;
+
+import com.sun.management.GarbageCollectionNotificationInfo;
+
+import javax.management.ListenerNotFoundException;
+import javax.management.Notification;
+import javax.management.NotificationEmitter;
+import javax.management.NotificationListener;
+import javax.management.openmbean.CompositeData;
+import java.lang.management.GarbageCollectorMXBean;
+import java.lang.management.ManagementFactory;
+import java.util.ArrayList;
+import java.util.List;
+
+public class GarbageCollectionMonitor implements NotificationListener, AutoCloseable {
+
+    private final List<Listener> listeners = new ArrayList<>();
+    private final List<NotificationEmitter> emitters = new ArrayList<>();
+
+    public GarbageCollectionMonitor() {
+        List<GarbageCollectorMXBean> beans = ManagementFactory.getGarbageCollectorMXBeans();
+        for (GarbageCollectorMXBean bean : beans) {
+            if (!(bean instanceof NotificationEmitter)) {
+                continue;
+            }
+
+            NotificationEmitter notificationEmitter = (NotificationEmitter) bean;
+            notificationEmitter.addNotificationListener(this, null, null);
+            this.emitters.add(notificationEmitter);
+        }
+    }
+
+    public void addListener(Listener listener) {
+        this.listeners.add(listener);
+    }
+
+    public void removeListener(Listener listener) {
+        this.listeners.remove(listener);
+    }
+
+    @Override
+    public void handleNotification(Notification notification, Object handback) {
+        if (!notification.getType().equals(GarbageCollectionNotificationInfo.GARBAGE_COLLECTION_NOTIFICATION)) {
+            return;
+        }
+
+        GarbageCollectionNotificationInfo data = GarbageCollectionNotificationInfo.from((CompositeData) notification.getUserData());
+        for (Listener listener : this.listeners) {
+            listener.onGc(data);
+        }
+    }
+
+    @Override
+    public void close() {
+        for (NotificationEmitter e : this.emitters) {
+            try {
+                e.removeNotificationListener(this);
+            } catch (ListenerNotFoundException ex) {
+                ex.printStackTrace();
+            }
+        }
+        this.emitters.clear();
+        this.listeners.clear();
+    }
+
+    public interface Listener {
+        void onGc(GarbageCollectionNotificationInfo data);
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/monitor/tick/TickMonitor.java b/spark-common/src/main/java/me/lucko/spark/common/monitor/tick/TickMonitor.java
new file mode 100644
index 0000000..034e876
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/monitor/tick/TickMonitor.java
@@ -0,0 +1,143 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.monitor.tick;
+
+import com.sun.management.GarbageCollectionNotificationInfo;
+import me.lucko.spark.common.monitor.gc.GarbageCollectionMonitor;
+import me.lucko.spark.common.sampler.TickCounter;
+
+import java.text.DecimalFormat;
+import java.util.DoubleSummaryStatistics;
+
+public abstract class TickMonitor implements TickCounter.TickTask, GarbageCollectionMonitor.Listener, AutoCloseable {
+    private static final DecimalFormat df = new DecimalFormat("#.##");
+
+    private final TickCounter tickCounter;
+    private final GarbageCollectionMonitor garbageCollectionMonitor;
+    private final int percentageChangeThreshold;
+
+    // data
+    private volatile double lastTickTime = 0;
+    private State state = null;
+    private final DoubleSummaryStatistics averageTickTime = new DoubleSummaryStatistics();
+    private double avg;
+
+    public TickMonitor(TickCounter tickCounter, int percentageChangeThreshold, boolean monitorGc) {
+        this.tickCounter = tickCounter;
+        this.percentageChangeThreshold = percentageChangeThreshold;
+
+        if (monitorGc) {
+            this.garbageCollectionMonitor =  new GarbageCollectionMonitor();
+            this.garbageCollectionMonitor.addListener(this);
+        } else {
+            this.garbageCollectionMonitor = null;
+        }
+    }
+
+    protected abstract void sendMessage(String message);
+
+    @Override
+    public void close() {
+        if (this.garbageCollectionMonitor != null) {
+            this.garbageCollectionMonitor.close();
+        }
+    }
+
+    @Override
+    public void onTick(TickCounter counter) {
+        double now = ((double) System.nanoTime()) / 1000000d;
+
+        // init
+        if (this.state == null) {
+            this.state = State.SETUP;
+            this.lastTickTime = now;
+            sendMessage("Tick monitor started. Before the monitor becomes fully active, the server's " +
+                    "average tick rate will be calculated over a period of 120 ticks (approx 6 seconds).");
+            return;
+        }
+
+        // find the diff
+        double last = this.lastTickTime;
+        double diff = now - last;
+        boolean ignore = last == 0;
+        this.lastTickTime = now;
+
+        if (ignore) {
+            return;
+        }
+
+        // form averages
+        if (this.state == State.SETUP) {
+            this.averageTickTime.accept(diff);
+
+            // move onto the next state
+            if (this.averageTickTime.getCount() >= 120) {
+
+                sendMessage("&bAnalysis is now complete.");
+                sendMessage("&f> &7Max: " + df.format(this.averageTickTime.getMax()) + "ms");
+                sendMessage("&f> &7Min: " + df.format(this.averageTickTime.getMin()) + "ms");
+                sendMessage("&f> &7Avg: " + df.format(this.averageTickTime.getAverage()) + "ms");
+                sendMessage("Starting now, any ticks with >" + this.percentageChangeThreshold + "% increase in " +
+                        "duration compared to the average will be reported.");
+
+                this.avg = this.averageTickTime.getAverage();
+                this.state = State.MONITORING;
+            }
+        }
+
+        if (this.state == State.MONITORING) {
+            double increase = diff - this.avg;
+            if (increase <= 0) {
+                return;
+            }
+
+            double percentageChange = (increase * 100d) / this.avg;
+            if (percentageChange > this.percentageChangeThreshold) {
+                sendMessage("&7Tick &8#" + counter.getCurrentTick() + " &7lasted &b" + df.format(diff) +
+                        "&7 ms. (&b" + df.format(percentageChange) + "% &7increase from average)");
+            }
+        }
+    }
+
+    @Override
+    public void onGc(GarbageCollectionNotificationInfo data) {
+        if (this.state == State.SETUP) {
+            // set lastTickTime to zero so this tick won't be counted in the average
+            this.lastTickTime = 0;
+            return;
+        }
+
+        String gcType = data.getGcAction();
+        if (gcType.equals("end of minor GC")) {
+            gcType = "Young Gen GC";
+        } else if (gcType.equals("end of major GC")) {
+            gcType = "Old Gen GC";
+        }
+
+        sendMessage("&7Tick &8#" + this.tickCounter.getCurrentTick() + " &7included &4GC &7lasting &b" +
+                df.format(data.getGcInfo().getDuration()) + "&7 ms. (type = " + gcType + ")");
+    }
+
+    private enum State {
+        SETUP,
+        MONITORING
+    }
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/monitor/tick/TpsCalculator.java b/spark-common/src/main/java/me/lucko/spark/common/monitor/tick/TpsCalculator.java
new file mode 100644
index 0000000..2f3af3e
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/monitor/tick/TpsCalculator.java
@@ -0,0 +1,170 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.monitor.tick;
+
+import me.lucko.spark.common.sampler.TickCounter;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Calculates the servers TPS (ticks per second) rate.
+ *
+ * <p>The code use to calculate the TPS is the same as the code used by the Minecraft server itself.
+ * This means that this class will output values the same as the /tps command.</p>
+ *
+ * <p>We calculate our own values instead of pulling them from the server for two reasons. Firstly,
+ * it's easier - pulling from the server requires reflection code on each of the platforms, we'd
+ * rather avoid that. Secondly, it allows us to generate rolling averages over a shorter period of
+ * time.</p>
+ */
+public class TpsCalculator implements TickCounter.TickTask {
+
+    private static final long SEC_IN_NANO = TimeUnit.SECONDS.toNanos(1);
+    private static final int TPS = 20;
+    private static final int SAMPLE_INTERVAL = 20;
+    private static final BigDecimal TPS_BASE = new BigDecimal(SEC_IN_NANO).multiply(new BigDecimal((long) SAMPLE_INTERVAL));
+
+    private final RollingAverage tps5S = new RollingAverage(5);
+    private final RollingAverage tps10S = new RollingAverage(10);
+    private final RollingAverage tps1M = new RollingAverage(60);
+    private final RollingAverage tps5M = new RollingAverage(60 * 5);
+    private final RollingAverage tps15M = new RollingAverage(60 * 15);
+
+    private final RollingAverage[] averages = new RollingAverage[]{
+            this.tps5S, this.tps10S, this.tps1M, this.tps5M, this.tps15M
+    };
+
+    private long last = 0;
+
+    // called every tick
+    @Override
+    public void onTick(TickCounter counter) {
+        if (counter.getCurrentTick() % SAMPLE_INTERVAL != 0) {
+            return;
+        }
+
+        long now = System.nanoTime();
+
+        if (this.last == 0) {
+            this.last = now;
+            return;
+        }
+
+        long diff = now - this.last;
+        BigDecimal currentTps = TPS_BASE.divide(new BigDecimal(diff), 30, RoundingMode.HALF_UP);
+
+        for (RollingAverage rollingAverage : this.averages) {
+            rollingAverage.add(currentTps, diff);
+        }
+
+        this.last = now;
+    }
+
+    public RollingAverage avg5Sec() {
+        return this.tps5S;
+    }
+
+    public RollingAverage avg10Sec() {
+        return this.tps10S;
+    }
+
+    public RollingAverage avg1Min() {
+        return this.tps1M;
+    }
+
+    public RollingAverage avg5Min() {
+        return this.tps5M;
+    }
+
+    public RollingAverage avg15Min() {
+        return this.tps15M;
+    }
+
+    public String toFormattedString() {
+        return formatTps(this.tps5S.getAverage()) + ", " +
+                formatTps(this.tps10S.getAverage()) + ", " +
+                formatTps(this.tps1M.getAverage()) + ", " +
+                formatTps(this.tps5M.getAverage()) + ", " +
+                formatTps(this.tps15M.getAverage());
+    }
+
+    public static String formatTps(double tps) {
+        StringBuilder sb = new StringBuilder();
+        if (tps > 18.0) {
+            sb.append("&a");
+        } else if (tps > 16.0) {
+            sb.append("&e");
+        } else {
+            sb.append("&c");
+        }
+        if (tps > 20.0) {
+            sb.append('*');
+        }
+        return sb.append(Math.min(Math.round(tps * 100.0) / 100.0, 20.0)).toString();
+    }
+
+    /**
+     * Rolling average calculator taken.
+     *
+     * <p>This code is taken from PaperMC/Paper, licensed under MIT.</p>
+     *
+     * @author aikar (PaperMC) https://github.com/PaperMC/Paper/blob/master/Spigot-Server-Patches/0021-Further-improve-server-tick-loop.patch
+     */
+    public static final class RollingAverage {
+        private final int size;
+        private long time;
+        private BigDecimal total;
+        private int index = 0;
+        private final BigDecimal[] samples;
+        private final long[] times;
+
+        RollingAverage(int size) {
+            this.size = size;
+            this.time = size * SEC_IN_NANO;
+            this.total = new BigDecimal((long) TPS).multiply(new BigDecimal(SEC_IN_NANO)).multiply(new BigDecimal((long) size));
+            this.samples = new BigDecimal[size];
+            this.times = new long[size];
+            for (int i = 0; i < size; i++) {
+                this.samples[i] = new BigDecimal((long) TPS);
+                this.times[i] = SEC_IN_NANO;
+            }
+        }
+
+        public void add(BigDecimal x, long t) {
+            this.time -= this.times[this.index];
+            this.total = this.total.subtract(this.samples[this.index].multiply(new BigDecimal(this.times[this.index])));
+            this.samples[this.index] = x;
+            this.times[this.index] = t;
+            this.time += t;
+            this.total = this.total.add(x.multiply(new BigDecimal(t)));
+            if (++this.index == this.size) {
+                this.index = 0;
+            }
+        }
+
+        public double getAverage() {
+            return this.total.divide(new BigDecimal(this.time), 30, RoundingMode.HALF_UP).doubleValue();
+        }
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/Sampler.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/Sampler.java
new file mode 100644
index 0000000..d504247
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/Sampler.java
@@ -0,0 +1,200 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (C) Albert Pham <http://www.sk89q.com>
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler;
+
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import com.google.gson.stream.JsonWriter;
+import me.lucko.spark.common.sampler.aggregator.DataAggregator;
+import me.lucko.spark.common.sampler.aggregator.SimpleDataAggregator;
+import me.lucko.spark.common.sampler.aggregator.TickedDataAggregator;
+import me.lucko.spark.common.sampler.node.ThreadNode;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.lang.management.ManagementFactory;
+import java.lang.management.ThreadInfo;
+import java.lang.management.ThreadMXBean;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.zip.GZIPOutputStream;
+
+/**
+ * Main sampler class.
+ */
+public class Sampler implements Runnable {
+    private static final AtomicInteger THREAD_ID = new AtomicInteger(0);
+
+    /** The worker pool for inserting stack nodes */
+    private final ScheduledExecutorService workerPool = Executors.newScheduledThreadPool(
+            6, new ThreadFactoryBuilder().setNameFormat("spark-worker-" + THREAD_ID.getAndIncrement() + "-%d").build()
+    );
+
+    /** The main sampling task */
+    private ScheduledFuture<?> task;
+
+    /** The thread management interface for the current JVM */
+    private final ThreadMXBean threadBean = ManagementFactory.getThreadMXBean();
+    /** The instance used to generate thread information for use in sampling */
+    private final ThreadDumper threadDumper;
+    /** Responsible for aggregating and then outputting collected sampling data */
+    private final DataAggregator dataAggregator;
+
+    /** A future to encapsulation the completion of this sampler instance */
+    private final CompletableFuture<Sampler> future = new CompletableFuture<>();
+
+    /** The interval to wait between sampling, in microseconds */
+    private final int interval;
+    /** The time when sampling first began */
+    private long startTime = -1;
+    /** The unix timestamp (in millis) when this sampler should automatically complete.*/
+    private final long endTime; // -1 for nothing
+    
+    public Sampler(int interval, ThreadDumper threadDumper, ThreadGrouper threadGrouper, long endTime, boolean includeLineNumbers) {
+        this.threadDumper = threadDumper;
+        this.dataAggregator = new SimpleDataAggregator(this.workerPool, threadGrouper, interval, includeLineNumbers);
+        this.interval = interval;
+        this.endTime = endTime;
+    }
+
+    public Sampler(int interval, ThreadDumper threadDumper, ThreadGrouper threadGrouper, long endTime, boolean includeLineNumbers, TickCounter tickCounter, int tickLengthThreshold) {
+        this.threadDumper = threadDumper;
+        this.dataAggregator = new TickedDataAggregator(this.workerPool, tickCounter, threadGrouper, interval, includeLineNumbers, tickLengthThreshold);
+        this.interval = interval;
+        this.endTime = endTime;
+    }
+
+    /**
+     * Starts the sampler.
+     */
+    public void start() {
+        this.startTime = System.currentTimeMillis();
+        this.dataAggregator.start();
+        this.task = this.workerPool.scheduleAtFixedRate(this, 0, this.interval, TimeUnit.MICROSECONDS);
+    }
+
+    public long getStartTime() {
+        if (this.startTime == -1) {
+            throw new IllegalStateException("Not yet started");
+        }
+        return this.startTime;
+    }
+
+    public long getEndTime() {
+        return this.endTime;
+    }
+
+    public CompletableFuture<Sampler> getFuture() {
+        return this.future;
+    }
+
+    public void cancel() {
+        this.task.cancel(false);
+    }
+
+    @Override
+    public void run() {
+        // this is effectively synchronized, the worker pool will not allow this task
+        // to concurrently execute.
+        try {
+            if (this.endTime != -1 && this.endTime <= System.currentTimeMillis()) {
+                this.future.complete(this);
+                cancel();
+                return;
+            }
+
+            ThreadInfo[] threadDumps = this.threadDumper.dumpThreads(this.threadBean);
+            this.workerPool.execute(new InsertDataTask(this.dataAggregator, threadDumps));
+        } catch (Throwable t) {
+            this.future.completeExceptionally(t);
+            cancel();
+        }
+    }
+
+    private static final class InsertDataTask implements Runnable {
+        private final DataAggregator dataAggregator;
+        private final ThreadInfo[] threadDumps;
+
+        InsertDataTask(DataAggregator dataAggregator, ThreadInfo[] threadDumps) {
+            this.dataAggregator = dataAggregator;
+            this.threadDumps = threadDumps;
+        }
+
+        @Override
+        public void run() {
+            for (ThreadInfo threadInfo : this.threadDumps) {
+                String threadName = threadInfo.getThreadName();
+                StackTraceElement[] stack = threadInfo.getStackTrace();
+
+                if (threadName == null || stack == null) {
+                    continue;
+                }
+
+                this.dataAggregator.insertData(threadName, stack);
+            }
+        }
+    }
+
+    private void writeOutput(JsonWriter writer) throws IOException {
+        writer.beginObject();
+
+        writer.name("type").value("sampler");
+        writer.name("threads").beginArray();
+
+        List<Map.Entry<String, ThreadNode>> data = new ArrayList<>(this.dataAggregator.getData().entrySet());
+        data.sort(Map.Entry.comparingByKey());
+
+        for (Map.Entry<String, ThreadNode> entry : data) {
+            writer.beginObject();
+            writer.name("threadName").value(entry.getKey());
+            writer.name("totalTime").value(entry.getValue().getTotalTime());
+            writer.name("rootNode");
+            entry.getValue().serializeTo(writer);
+            writer.endObject();
+        }
+
+        writer.endArray();
+        writer.endObject();
+    }
+
+    public byte[] formCompressedDataPayload() {
+        ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
+        try (Writer writer = new OutputStreamWriter(new GZIPOutputStream(byteOut), StandardCharsets.UTF_8)) {
+            try (JsonWriter jsonWriter = new JsonWriter(writer)) {
+                writeOutput(jsonWriter);
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+        return byteOut.toByteArray();
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerBuilder.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerBuilder.java
new file mode 100644
index 0000000..4ce69df
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/SamplerBuilder.java
@@ -0,0 +1,90 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Builds {@link Sampler} instances.
+ */
+public class SamplerBuilder {
+
+    private double samplingInterval = 4; // milliseconds
+    private boolean includeLineNumbers = false;
+    private long timeout = -1;
+    private ThreadDumper threadDumper = ThreadDumper.ALL;
+    private ThreadGrouper threadGrouper = ThreadGrouper.BY_NAME;
+
+    private int ticksOver = -1;
+    private TickCounter tickCounter = null;
+
+    public SamplerBuilder() {
+    }
+
+    public SamplerBuilder samplingInterval(double samplingInterval) {
+        this.samplingInterval = samplingInterval;
+        return this;
+    }
+
+    public SamplerBuilder completeAfter(long timeout, TimeUnit unit) {
+        if (timeout <= 0) {
+            throw new IllegalArgumentException("timeout > 0");
+        }
+        this.timeout = System.currentTimeMillis() + unit.toMillis(timeout);
+        return this;
+    }
+
+    public SamplerBuilder threadDumper(ThreadDumper threadDumper) {
+        this.threadDumper = threadDumper;
+        return this;
+    }
+
+    public SamplerBuilder threadGrouper(ThreadGrouper threadGrouper) {
+        this.threadGrouper = threadGrouper;
+        return this;
+    }
+
+    public SamplerBuilder ticksOver(int ticksOver, TickCounter tickCounter) {
+        this.ticksOver = ticksOver;
+        this.tickCounter = tickCounter;
+        return this;
+    }
+
+    public SamplerBuilder includeLineNumbers(boolean includeLineNumbers) {
+        this.includeLineNumbers = includeLineNumbers;
+        return this;
+    }
+
+    public Sampler start() {
+        Sampler sampler;
+
+        int intervalMicros = (int) (this.samplingInterval * 1000d);
+        if (this.ticksOver != -1 && this.tickCounter != null) {
+            sampler = new Sampler(intervalMicros, this.threadDumper, this.threadGrouper, this.timeout, this.includeLineNumbers, this.tickCounter, this.ticksOver);
+        } else {
+            sampler = new Sampler(intervalMicros, this.threadDumper, this.threadGrouper, this.timeout, this.includeLineNumbers);
+        }
+
+        sampler.start();
+        return sampler;
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/ThreadDumper.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/ThreadDumper.java
new file mode 100644
index 0000000..14938ac
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/ThreadDumper.java
@@ -0,0 +1,126 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (C) Albert Pham <http://www.sk89q.com>
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler;
+
+import me.lucko.spark.common.util.ThreadFinder;
+
+import java.lang.management.ThreadInfo;
+import java.lang.management.ThreadMXBean;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
+import java.util.stream.Collectors;
+
+/**
+ * Uses the {@link ThreadMXBean} to generate {@link ThreadInfo} instances for the threads being
+ * sampled.
+ */
+@FunctionalInterface
+public interface ThreadDumper {
+
+    /**
+     * Generates {@link ThreadInfo} data for the sampled threads.
+     *
+     * @param threadBean the thread bean instance to obtain the data from
+     * @return an array of generated thread info instances
+     */
+    ThreadInfo[] dumpThreads(ThreadMXBean threadBean);
+
+    /**
+     * Implementation of {@link ThreadDumper} that generates data for all threads.
+     */
+    ThreadDumper ALL = threadBean -> threadBean.dumpAllThreads(false, false);
+
+    /**
+     * Implementation of {@link ThreadDumper} that generates data for a specific set of threads.
+     */
+    final class Specific implements ThreadDumper {
+        private final ThreadFinder threadFinder = new ThreadFinder();
+        private final long[] ids;
+
+        public Specific(long[] ids) {
+            this.ids = ids;
+        }
+
+        public Specific(Set<String> names) {
+            Set<String> namesLower = names.stream().map(String::toLowerCase).collect(Collectors.toSet());
+            this.ids = this.threadFinder.getThreads()
+                    .filter(t -> namesLower.contains(t.getName().toLowerCase()))
+                    .mapToLong(Thread::getId)
+                    .toArray();
+        }
+
+        @Override
+        public ThreadInfo[] dumpThreads(ThreadMXBean threadBean) {
+            return threadBean.getThreadInfo(this.ids, Integer.MAX_VALUE);
+        }
+    }
+
+    /**
+     * Implementation of {@link ThreadDumper} that generates data for a regex matched set of threads.
+     */
+    final class Regex implements ThreadDumper {
+        private final ThreadFinder threadFinder = new ThreadFinder();
+        private final Set<Pattern> namePatterns;
+        private final Map<Long, Boolean> cache = new HashMap<>();
+
+        public Regex(Set<String> namePatterns) {
+            this.namePatterns = namePatterns.stream()
+                    .map(regex -> {
+                        try {
+                            return Pattern.compile(regex);
+                        } catch (PatternSyntaxException e) {
+                            return null;
+                        }
+                    })
+                    .filter(Objects::nonNull)
+                    .collect(Collectors.toSet());
+        }
+
+        @Override
+        public ThreadInfo[] dumpThreads(ThreadMXBean threadBean) {
+            return this.threadFinder.getThreads()
+                    .filter(thread -> {
+                        Boolean result = this.cache.get(thread.getId());
+                        if (result != null) {
+                            return result;
+                        }
+
+                        for (Pattern pattern : this.namePatterns) {
+                            if (pattern.matcher(thread.getName()).matches()) {
+                                this.cache.put(thread.getId(), true);
+                                return true;
+                            }
+                        }
+                        this.cache.put(thread.getId(), false);
+                        return false;
+                    })
+                    .map(thread -> threadBean.getThreadInfo(thread.getId()))
+                    .filter(Objects::nonNull)
+                    .toArray(ThreadInfo[]::new);
+        }
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/ThreadGrouper.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/ThreadGrouper.java
new file mode 100644
index 0000000..f53800a
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/ThreadGrouper.java
@@ -0,0 +1,72 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Function for grouping threads together
+ */
+@FunctionalInterface
+public interface ThreadGrouper {
+
+    /**
+     * Gets the group for the given thread.
+     *
+     * @param threadName the name of the thread
+     * @return the group
+     */
+    String getGroup(String threadName);
+
+    /**
+     * Implementation of {@link ThreadGrouper} that just groups by thread name.
+     */
+    ThreadGrouper BY_NAME = threadName -> threadName;
+
+    /**
+     * Implementation of {@link ThreadGrouper} that attempts to group by the name of the pool
+     * the thread originated from.
+     *
+     * <p>The regex pattern used to match pools expects a digit at the end of the thread name,
+     * separated from the pool name with any of one or more of ' ', '-', or '#'.</p>
+     */
+    ThreadGrouper BY_POOL = new ThreadGrouper() {
+        private final Pattern pattern = Pattern.compile("^(.*?)[-# ]+\\d+$");
+
+        @Override
+        public String getGroup(String threadName) {
+            Matcher matcher = this.pattern.matcher(threadName);
+            if (!matcher.matches()) {
+                return threadName;
+            }
+
+            return matcher.group(1).trim() + " (Combined)";
+        }
+    };
+
+    /**
+     * Implementation of {@link ThreadGrouper} which groups all threads as one, under
+     * the name "All".
+     */
+    ThreadGrouper AS_ONE = threadName -> "All";
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/TickCounter.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/TickCounter.java
new file mode 100644
index 0000000..aa839ba
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/TickCounter.java
@@ -0,0 +1,64 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler;
+
+/**
+ * A hook with the game's "tick loop".
+ */
+public interface TickCounter extends AutoCloseable {
+
+    /**
+     * Starts the counter
+     */
+    void start();
+
+    /**
+     * Stops the counter
+     */
+    @Override
+    void close();
+
+    /**
+     * Gets the current tick number
+     *
+     * @return the current tick
+     */
+    int getCurrentTick();
+
+    /**
+     * Adds a task to be called each time the tick increments
+     *
+     * @param runnable the task
+     */
+    void addTickTask(TickTask runnable);
+
+    /**
+     * Removes a tick task
+     *
+     * @param runnable the task
+     */
+    void removeTickTask(TickTask runnable);
+
+    interface TickTask {
+        void onTick(TickCounter counter);
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/DataAggregator.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/DataAggregator.java
new file mode 100644
index 0000000..8c65c2d
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/DataAggregator.java
@@ -0,0 +1,54 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler.aggregator;
+
+import me.lucko.spark.common.sampler.node.ThreadNode;
+
+import java.util.Map;
+
+/**
+ * Aggregates sampling data.
+ */
+public interface DataAggregator {
+
+    /**
+     * Called before the sampler begins to insert data
+     */
+    default void start() {
+
+    }
+
+    /**
+     * Forms the output data
+     *
+     * @return the output data
+     */
+    Map<String, ThreadNode> getData();
+
+    /**
+     * Inserts sampling data into this aggregator
+     *
+     * @param threadName the name of the thread
+     * @param stack the call stack
+     */
+    void insertData(String threadName, StackTraceElement[] stack);
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/SimpleDataAggregator.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/SimpleDataAggregator.java
new file mode 100644
index 0000000..8fbd03f
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/SimpleDataAggregator.java
@@ -0,0 +1,82 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler.aggregator;
+
+import me.lucko.spark.common.sampler.ThreadGrouper;
+import me.lucko.spark.common.sampler.node.AbstractNode;
+import me.lucko.spark.common.sampler.node.ThreadNode;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Basic implementation of {@link DataAggregator}.
+ */
+public class SimpleDataAggregator implements DataAggregator {
+
+    /** A map of root stack nodes for each thread with sampling data */
+    private final Map<String, ThreadNode> threadData = new ConcurrentHashMap<>();
+
+    /** The worker pool used for sampling */
+    private final ExecutorService workerPool;
+
+    /** The instance used to group threads together */
+    private final ThreadGrouper threadGrouper;
+
+    /** The interval to wait between sampling, in microseconds */
+    private final int interval;
+
+    /** If line numbers should be included in the output */
+    private final boolean includeLineNumbers;
+
+    public SimpleDataAggregator(ExecutorService workerPool, ThreadGrouper threadGrouper, int interval, boolean includeLineNumbers) {
+        this.workerPool = workerPool;
+        this.threadGrouper = threadGrouper;
+        this.interval = interval;
+        this.includeLineNumbers = includeLineNumbers;
+    }
+
+    @Override
+    public void insertData(String threadName, StackTraceElement[] stack) {
+        try {
+            String group = this.threadGrouper.getGroup(threadName);
+            AbstractNode node = this.threadData.computeIfAbsent(group, ThreadNode::new);
+            node.log(stack, this.interval, this.includeLineNumbers);
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+    @Override
+    public Map<String, ThreadNode> getData() {
+        // wait for all pending data to be inserted
+        this.workerPool.shutdown();
+        try {
+            this.workerPool.awaitTermination(15, TimeUnit.SECONDS);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+
+        return this.threadData;
+    }
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/TickedDataAggregator.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/TickedDataAggregator.java
new file mode 100644
index 0000000..8f8124b
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/aggregator/TickedDataAggregator.java
@@ -0,0 +1,184 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler.aggregator;
+
+import me.lucko.spark.common.sampler.ThreadGrouper;
+import me.lucko.spark.common.sampler.TickCounter;
+import me.lucko.spark.common.sampler.node.AbstractNode;
+import me.lucko.spark.common.sampler.node.ThreadNode;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Implementation of {@link DataAggregator} which supports only including sampling data from "ticks"
+ * which exceed a certain threshold in duration.
+ */
+public class TickedDataAggregator implements DataAggregator {
+
+    /** A map of root stack nodes for each thread with sampling data */
+    private final Map<String, ThreadNode> threadData = new ConcurrentHashMap<>();
+
+    /** The worker pool for inserting stack nodes */
+    private final ExecutorService workerPool;
+
+    /** Used to monitor the current "tick" of the server */
+    private final TickCounter tickCounter;
+
+    /** The instance used to group threads together */
+    private final ThreadGrouper threadGrouper;
+
+    /** The interval to wait between sampling, in microseconds */
+    private final int interval;
+
+    /** If line numbers should be included in the output */
+    private final boolean includeLineNumbers;
+
+    /** Tick durations under this threshold will not be inserted, measured in microseconds */
+    private final long tickLengthThreshold;
+
+    /** The expected number of samples in each tick */
+    private final int expectedSize;
+
+    private final Object mutex = new Object();
+
+    // state
+    private int currentTick = -1;
+    private TickList currentData = new TickList(0);
+
+    public TickedDataAggregator(ExecutorService workerPool, TickCounter tickCounter, ThreadGrouper threadGrouper, int interval, boolean includeLineNumbers, int tickLengthThreshold) {
+        this.workerPool = workerPool;
+        this.tickCounter = tickCounter;
+        this.threadGrouper = threadGrouper;
+        this.interval = interval;
+        this.includeLineNumbers = includeLineNumbers;
+        this.tickLengthThreshold = TimeUnit.MILLISECONDS.toMicros(tickLengthThreshold);
+        // 50 millis in a tick, plus 10 so we have a bit of room to go over
+        double intervalMilliseconds = interval / 1000d;
+        this.expectedSize = (int) ((50 / intervalMilliseconds) + 10);
+    }
+
+    @Override
+    public void insertData(String threadName, StackTraceElement[] stack) {
+        synchronized (this.mutex) {
+            int tick = this.tickCounter.getCurrentTick();
+            if (this.currentTick != tick) {
+                pushCurrentTick();
+                this.currentTick = tick;
+                this.currentData = new TickList(this.expectedSize);
+            }
+
+            // form the queued data
+            QueuedThreadInfo queuedData = new QueuedThreadInfo(threadName, stack);
+            // insert it
+            this.currentData.addData(queuedData);
+        }
+    }
+
+    // guarded by 'mutex'
+    private void pushCurrentTick() {
+        TickList currentData = this.currentData;
+
+        // approximate how long the tick lasted
+        int tickLengthMicros = currentData.getList().size() * this.interval;
+
+        // don't push data below the threshold
+        if (tickLengthMicros < this.tickLengthThreshold) {
+            return;
+        }
+
+        this.workerPool.submit(currentData);
+    }
+
+    @Override
+    public void start() {
+        this.tickCounter.start();
+    }
+
+    @Override
+    public Map<String, ThreadNode> getData() {
+        // push the current tick
+        synchronized (this.mutex) {
+            pushCurrentTick();
+        }
+
+        // close the tick counter
+        this.tickCounter.close();
+
+        // wait for all pending data to be inserted
+        this.workerPool.shutdown();
+        try {
+            this.workerPool.awaitTermination(15, TimeUnit.SECONDS);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+
+        return this.threadData;
+    }
+
+    // called by TickList
+    void insertData(List<QueuedThreadInfo> dataList) {
+        for (QueuedThreadInfo data : dataList) {
+            try {
+                String group = this.threadGrouper.getGroup(data.threadName);
+                AbstractNode node = this.threadData.computeIfAbsent(group, ThreadNode::new);
+                node.log(data.stack, this.interval, this.includeLineNumbers);
+            } catch (Exception e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    private final class TickList implements Runnable {
+        private final List<QueuedThreadInfo> list;
+
+        TickList(int expectedSize) {
+            this.list = new ArrayList<>(expectedSize);
+        }
+
+        @Override
+        public void run() {
+            insertData(this.list);
+        }
+
+        public List<QueuedThreadInfo> getList() {
+            return this.list;
+        }
+
+        public void addData(QueuedThreadInfo data) {
+            this.list.add(data);
+        }
+    }
+
+    private static final class QueuedThreadInfo {
+        private final String threadName;
+        private final StackTraceElement[] stack;
+
+        QueuedThreadInfo(String threadName, StackTraceElement[] stack) {
+            this.threadName = threadName;
+            this.stack = stack;
+        }
+    }
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/node/AbstractNode.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/AbstractNode.java
new file mode 100644
index 0000000..5cfc0f2
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/AbstractNode.java
@@ -0,0 +1,143 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (C) Albert Pham <http://www.sk89q.com>
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler.node;
+
+import com.google.gson.stream.JsonWriter;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.LongAdder;
+
+/**
+ * Encapsulates a timed node in the sampling stack.
+ */
+public abstract class AbstractNode {
+
+    private static final int MAX_STACK_DEPTH = 300;
+
+    /**
+     * A map of this nodes children
+     */
+    private final Map<String, StackTraceNode> children = new ConcurrentHashMap<>();
+
+    /**
+     * The accumulated sample time for this node, measured in microseconds
+     */
+    private final LongAdder totalTime = new LongAdder();
+
+    /**
+     * Returns the total sample time for this node in milliseconds.
+     *
+     * @return the total time
+     */
+    public long getTotalTime() {
+        long millis = TimeUnit.MICROSECONDS.toMillis(this.totalTime.longValue());
+        if (millis == 0) {
+            return 1;
+        }
+        return millis;
+    }
+
+    private AbstractNode resolveChild(String className, String methodName, int lineNumber) {
+        return this.children.computeIfAbsent(
+                StackTraceNode.generateKey(className, methodName, lineNumber),
+                name -> new StackTraceNode(className, methodName, lineNumber)
+        );
+    }
+
+    public void log(StackTraceElement[] elements, long time, boolean includeLineNumbers) {
+        log(elements, 0, time, includeLineNumbers);
+    }
+    
+    private void log(StackTraceElement[] elements, int offset, long time, boolean includeLineNumbers) {
+        this.totalTime.add(time);
+
+        if (offset >= MAX_STACK_DEPTH) {
+            return;
+        }
+        
+        if (elements.length - offset == 0) {
+            return;
+        }
+
+        // the first element in the array is the top of the call stack, and the last is the root
+        // offset starts at 0.
+
+        // pointer is determined by subtracting the offset from the index of the last element
+        int pointer = (elements.length - 1) - offset;
+        StackTraceElement element = elements[pointer];
+
+        // the parent stack element is located at pointer+1.
+        // when the current offset is 0, we know the current pointer is at the last element in the
+        // array (the root) and therefore there is no parent.
+        StackTraceElement parent = offset == 0 ? null : elements[pointer + 1];
+
+        // get the line number of the parent element - the line which called "us"
+        int lineNumber = parent == null || !includeLineNumbers ? StackTraceNode.NULL_LINE_NUMBER : parent.getLineNumber();
+
+        // resolve a child element within the structure for the element at pointer
+        AbstractNode child = resolveChild(element.getClassName(), element.getMethodName(), lineNumber);
+        // call the log method on the found child, with an incremented offset.
+        child.log(elements, offset + 1, time, includeLineNumbers);
+    }
+
+    private Collection<? extends AbstractNode> getChildren() {
+        if (this.children.isEmpty()) {
+            return Collections.emptyList();
+        }
+
+        List<StackTraceNode> list = new ArrayList<>(this.children.values());
+        list.sort(null);
+        return list;
+    }
+
+    public void serializeTo(JsonWriter writer) throws IOException {
+        writer.beginObject();
+
+        // append metadata about this node
+        appendMetadata(writer);
+
+        // include the total time recorded for this node
+        writer.name("t").value(getTotalTime());
+
+        // append child nodes, if any are present
+        Collection<? extends AbstractNode> childNodes = getChildren();
+        if (!childNodes.isEmpty()) {
+            writer.name("c").beginArray();
+            for (AbstractNode child : childNodes) {
+                child.serializeTo(writer);
+            }
+            writer.endArray();
+        }
+
+        writer.endObject();
+    }
+
+    protected abstract void appendMetadata(JsonWriter writer) throws IOException;
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/node/StackTraceNode.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/StackTraceNode.java
new file mode 100644
index 0000000..c4e7ac4
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/StackTraceNode.java
@@ -0,0 +1,86 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (C) Albert Pham <http://www.sk89q.com>
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler.node;
+
+import com.google.gson.stream.JsonWriter;
+
+import java.io.IOException;
+
+/**
+ * Represents a stack trace element within the {@link AbstractNode node} structure.
+ */
+public final class StackTraceNode extends AbstractNode implements Comparable<StackTraceNode> {
+
+    /**
+     * Magic number to denote "no present" line number for a node.
+     */
+    public static final int NULL_LINE_NUMBER = -1;
+
+    /**
+     * Forms a key to represent the given node.
+     *
+     * @param className the name of the class
+     * @param methodName the name of the method
+     * @param lineNumber the line number of the parent method call
+     * @return the key
+     */
+    static String generateKey(String className, String methodName, int lineNumber) {
+        return className + "." + methodName + "." + lineNumber;
+    }
+
+    /** The name of the class */
+    private final String className;
+    /** The name of the method */
+    private final String methodName;
+    /** The line number of the invocation which created this node */
+    private final int lineNumber;
+
+    public StackTraceNode(String className, String methodName, int lineNumber) {
+        this.className = className;
+        this.methodName = methodName;
+        this.lineNumber = lineNumber;
+    }
+
+    @Override
+    protected void appendMetadata(JsonWriter writer) throws IOException {
+        writer.name("cl").value(this.className);
+        writer.name("m").value(this.methodName);
+        if (this.lineNumber >= 0) {
+            writer.name("ln").value(this.lineNumber);
+        }
+    }
+
+    private String key() {
+        return generateKey(this.className, this.methodName, this.lineNumber);
+    }
+
+    @Override
+    public int compareTo(StackTraceNode that) {
+        int i = -Long.compare(this.getTotalTime(), that.getTotalTime());
+        if (i != 0) {
+            return i;
+        }
+
+        return this.key().compareTo(that.key());
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/node/ThreadNode.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/ThreadNode.java
new file mode 100644
index 0000000..4e8714c
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/node/ThreadNode.java
@@ -0,0 +1,44 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.sampler.node;
+
+import com.google.gson.stream.JsonWriter;
+
+import java.io.IOException;
+
+/**
+ * The root of a sampling stack for a given thread / thread group.
+ */
+public final class ThreadNode extends AbstractNode {
+
+    /**
+     * The name of this thread
+     */
+    private final String threadName;
+
+    public ThreadNode(String threadName) {
+        this.threadName = threadName;
+    }
+
+    protected void appendMetadata(JsonWriter writer) throws IOException {
+        writer.name("name").value(this.threadName);
+    }
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/util/AbstractHttpClient.java b/spark-common/src/main/java/me/lucko/spark/common/util/AbstractHttpClient.java
new file mode 100644
index 0000000..1ff169d
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/util/AbstractHttpClient.java
@@ -0,0 +1,45 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.util;
+
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+
+import java.io.IOException;
+
+public class AbstractHttpClient {
+
+    /** The http client */
+    protected final OkHttpClient okHttp;
+
+    public AbstractHttpClient(OkHttpClient okHttp) {
+        this.okHttp = okHttp;
+    }
+
+    protected Response makeHttpRequest(Request request) throws IOException {
+        Response response = this.okHttp.newCall(request).execute();
+        if (!response.isSuccessful()) {
+            throw new RuntimeException("Request was unsuccessful: " + response.code() + " - " + response.message());
+        }
+        return response;
+    }
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/util/BytebinClient.java b/spark-common/src/main/java/me/lucko/spark/common/util/BytebinClient.java
new file mode 100644
index 0000000..ff8f4e3
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/util/BytebinClient.java
@@ -0,0 +1,149 @@
+/*
+ * This file is part of bytebin, licensed under the MIT License.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+package me.lucko.spark.common.util;
+
+import okhttp3.MediaType;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.RequestBody;
+import okhttp3.Response;
+
+import java.io.IOException;
+
+/**
+ * Utility for posting content to bytebin.
+ */
+public class BytebinClient extends AbstractHttpClient {
+
+    /** The bytebin URL */
+    private final String url;
+    /** The client user agent */
+    private final String userAgent;
+
+    /**
+     * Creates a new bytebin instance
+     *
+     * @param url the bytebin url
+     * @param userAgent the client user agent string
+     */
+    public BytebinClient(OkHttpClient okHttpClient, String url, String userAgent) {
+        super(okHttpClient);
+        if (url.endsWith("/")) {
+            this.url = url;
+        } else {
+            this.url = url + "/";
+        }
+        this.userAgent = userAgent;
+    }
+
+    /**
+     * POSTs GZIP compressed content to bytebin.
+     *
+     * @param buf the compressed content
+     * @param contentType the type of the content
+     * @param allowModification if the paste should be modifiable
+     * @return the key of the resultant content
+     * @throws IOException if an error occurs
+     */
+    public Content postContent(byte[] buf, MediaType contentType, boolean allowModification) throws IOException {
+        RequestBody body = RequestBody.create(contentType, buf);
+
+        Request.Builder requestBuilder = new Request.Builder()
+                .url(this.url + "post")
+                .header("User-Agent", this.userAgent)
+                .header("Content-Encoding", "gzip");
+
+        if (allowModification) {
+            requestBuilder.header("Allow-Modification", "true");
+        }
+
+        Request request = requestBuilder.post(body).build();
+        try (Response response = makeHttpRequest(request)) {
+            String key = response.header("Location");
+            if (key == null) {
+                throw new IllegalStateException("Key not returned");
+            }
+
+            if (allowModification) {
+                String modificationKey = response.header("Modification-Key");
+                if (modificationKey == null) {
+                    throw new IllegalStateException("Modification key not returned");
+                }
+                return new Content(key, modificationKey);
+            } else {
+                return new Content(key);
+            }
+        }
+    }
+
+    /**
+     * PUTs modified GZIP compressed content to bytebin in place of existing content.
+     *
+     * @param existingContent the existing content
+     * @param buf the compressed content to put
+     * @param contentType the type of the content
+     * @throws IOException if an error occurs
+     */
+    public void modifyContent(Content existingContent, byte[] buf, MediaType contentType) throws IOException {
+        if (!existingContent.modifiable) {
+            throw new IllegalArgumentException("Existing content is not modifiable");
+        }
+
+        RequestBody body = RequestBody.create(contentType, buf);
+
+        Request.Builder requestBuilder = new Request.Builder()
+                .url(this.url + existingContent.key())
+                .header("User-Agent", this.userAgent)
+                .header("Content-Encoding", "gzip")
+                .header("Modification-Key", existingContent.modificationKey);
+
+        Request request = requestBuilder.put(body).build();
+        makeHttpRequest(request).close();
+    }
+
+    public static final class Content {
+        private final String key;
+        private final boolean modifiable;
+        private final String modificationKey;
+
+        Content(String key) {
+            this.key = key;
+            this.modifiable = false;
+            this.modificationKey = null;
+        }
+
+        Content(String key, String modificationKey) {
+            this.key = key;
+            this.modifiable = true;
+            this.modificationKey = modificationKey;
+        }
+
+        public String key() {
+            return this.key;
+        }
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/util/ThreadFinder.java b/spark-common/src/main/java/me/lucko/spark/common/util/ThreadFinder.java
new file mode 100644
index 0000000..cc0722a
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/util/ThreadFinder.java
@@ -0,0 +1,60 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.util;
+
+import java.util.Arrays;
+import java.util.Objects;
+import java.util.stream.Stream;
+
+/**
+ * Utility to find active threads.
+ */
+public final class ThreadFinder {
+
+    private static final ThreadGroup ROOT_THREAD_GROUP;
+    static {
+        ThreadGroup rootGroup = Thread.currentThread().getThreadGroup();
+        ThreadGroup parentGroup;
+        while ((parentGroup = rootGroup.getParent()) != null) {
+            rootGroup = parentGroup;
+        }
+        ROOT_THREAD_GROUP = rootGroup;
+    }
+
+    // cache the approx active count at the time of construction.
+    // the usages of this class are likely to be somewhat short-lived, so it's good
+    // enough to just cache a value on init.
+    private final int approxActiveCount = ROOT_THREAD_GROUP.activeCount();
+
+    /**
+     * Gets a stream of all known active threads.
+     *
+     * @return a stream of threads
+     */
+    public Stream<Thread> getThreads() {
+        Thread[] threads = new Thread[this.approxActiveCount + 20]; // +20 to allow a bit of growth for newly created threads
+        while (ROOT_THREAD_GROUP.enumerate(threads, true) == threads.length) {
+            threads = new Thread[threads.length * 2];
+        }
+        return Arrays.stream(threads).filter(Objects::nonNull);
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/util/TypeDescriptors.java b/spark-common/src/main/java/me/lucko/spark/common/util/TypeDescriptors.java
new file mode 100644
index 0000000..a232e77
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/util/TypeDescriptors.java
@@ -0,0 +1,81 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.util;
+
+/**
+ * Utilities for working with Java type descriptors.
+ */
+public final class TypeDescriptors {
+
+    /**
+     * Returns the Java type corresponding to the given type descriptor.
+     *
+     * @param typeDescriptor a type descriptor.
+     * @return the Java type corresponding to the given type descriptor.
+     */
+    public static String getJavaType(String typeDescriptor) {
+        return getJavaType(typeDescriptor.toCharArray(), 0);
+    }
+
+    private static String getJavaType(char[] buf, int offset) {
+        int len;
+        switch (buf[offset]) {
+            case 'V':
+                return "void";
+            case 'Z':
+                return "boolean";
+            case 'C':
+                return "char";
+            case 'B':
+                return "byte";
+            case 'S':
+                return "short";
+            case 'I':
+                return "int";
+            case 'F':
+                return "float";
+            case 'J':
+                return "long";
+            case 'D':
+                return "double";
+            case '[': // array
+                len = 1;
+                while (buf[offset + len] == '[') {
+                    len++;
+                }
+
+                StringBuilder sb = new StringBuilder(getJavaType(buf, offset + len));
+                for (int i = len; i > 0; --i) {
+                    sb.append("[]");
+                }
+                return sb.toString();
+            case 'L': // object
+                len = 1;
+                while (buf[offset + len] != ';') {
+                    len++;
+                }
+                return new String(buf, offset + 1, len - 1);
+            default:
+                return new String(buf, offset, buf.length - offset);
+        }
+    }
+
+}