From a06e7f64ec3e47385a8f00de2dd6a4f01f96089a Mon Sep 17 00:00:00 2001
From: miclebrick <miclebrick@outlook.com>
Date: Wed, 8 Aug 2018 15:30:52 -0400
Subject: [PATCH] Add Early Warning Feature to WatchDog

Detect when the server has been hung for a long duration, and start printing
thread dumps at an interval until the point of crash.

This will help diagnose what was going on in that time before the crash.

diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
index adef07d4d..214b577b3 100644
--- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
@@ -24,6 +24,7 @@ import org.bukkit.configuration.file.YamlConfiguration;
 import co.aikar.timings.Timings;
 import co.aikar.timings.TimingsManager;
 import org.spigotmc.SpigotConfig;
+import org.spigotmc.WatchdogThread;
 
 public class PaperConfig {
 
@@ -288,6 +289,14 @@ public class PaperConfig {
         }
     }
 
+    public static int watchdogPrintEarlyWarningEvery = 5000;
+    public static int watchdogPrintEarlyWarningDelay = 10000;
+    private static void watchdogEarlyWarning() {
+        watchdogPrintEarlyWarningEvery = getInt("settings.watchdog.early-warning-every", 5000);
+        watchdogPrintEarlyWarningDelay = getInt("settings.watchdog.early-warning-delay", 10000);
+        WatchdogThread.doStart(SpigotConfig.timeoutTime, SpigotConfig.restartOnCrash );
+    }
+
     public static int tabSpamIncrement = 1;
     public static int tabSpamLimit = 500;
     private static void tabSpamLimiters() {
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index e75e976ff..1251f4581 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -869,6 +869,7 @@ public abstract class MinecraftServer extends IAsyncTaskHandlerReentrant<TickTas
                 this.a(this.serverPing);
 
                 // Spigot start
+                org.spigotmc.WatchdogThread.hasStarted = true; // Paper
                 Arrays.fill( recentTps, 20 );
                 long start = System.nanoTime(), curTime, tickSection = start; // Paper - Further improve server tick loop
                 lastTick = start - TICK_TIME; // Paper
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
index 296a11f14..8636283fd 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -758,6 +758,7 @@ public final class CraftServer implements Server {
 
     @Override
     public void reload() {
+        org.spigotmc.WatchdogThread.hasStarted = false; // Paper - Disable watchdog early timeout on reload
         reloadCount++;
         configuration = YamlConfiguration.loadConfiguration(getConfigFile());
         commandsConfiguration = YamlConfiguration.loadConfiguration(getCommandsConfigFile());
@@ -858,6 +859,7 @@ public final class CraftServer implements Server {
         enablePlugins(PluginLoadOrder.STARTUP);
         enablePlugins(PluginLoadOrder.POSTWORLD);
         getPluginManager().callEvent(new ServerLoadEvent(ServerLoadEvent.LoadType.RELOAD));
+        org.spigotmc.WatchdogThread.hasStarted = true; // Paper - Disable watchdog early timeout on reload
     }
 
     @Override
diff --git a/src/main/java/org/spigotmc/SpigotConfig.java b/src/main/java/org/spigotmc/SpigotConfig.java
index 1cf214eac..e66050b87 100644
--- a/src/main/java/org/spigotmc/SpigotConfig.java
+++ b/src/main/java/org/spigotmc/SpigotConfig.java
@@ -225,7 +225,7 @@ public class SpigotConfig
         restartScript = getString( "settings.restart-script", restartScript );
         restartMessage = transform( getString( "messages.restart", "Server is restarting" ) );
         commands.put( "restart", new RestartCommand( "restart" ) );
-        WatchdogThread.doStart( timeoutTime, restartOnCrash );
+        //WatchdogThread.doStart( timeoutTime, restartOnCrash ); // Paper - moved to PaperConfig
     }
 
     public static boolean bungee;
diff --git a/src/main/java/org/spigotmc/WatchdogThread.java b/src/main/java/org/spigotmc/WatchdogThread.java
index 121c7ff60..07936eeba 100644
--- a/src/main/java/org/spigotmc/WatchdogThread.java
+++ b/src/main/java/org/spigotmc/WatchdogThread.java
@@ -5,6 +5,7 @@ import java.lang.management.MonitorInfo;
 import java.lang.management.ThreadInfo;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import com.destroystokyo.paper.PaperConfig;
 import net.minecraft.server.MinecraftServer;
 import org.bukkit.Bukkit;
 
@@ -13,6 +14,10 @@ public class WatchdogThread extends Thread
 
     private static WatchdogThread instance;
     private final long timeoutTime;
+    private final long earlyWarningEvery; // Paper - Timeout time for just printing a dump but not restarting
+    private final long earlyWarningDelay; // Paper
+    public static volatile boolean hasStarted; // Paper
+    private long lastEarlyWarning; // Paper - Keep track of short dump times to avoid spamming console with short dumps
     private final boolean restart;
     private volatile long lastTick;
     private volatile boolean stopping;
@@ -22,6 +27,8 @@ public class WatchdogThread extends Thread
         super( "Paper Watchdog Thread" );
         this.timeoutTime = timeoutTime;
         this.restart = restart;
+        earlyWarningEvery = Math.min(PaperConfig.watchdogPrintEarlyWarningEvery, timeoutTime); // Paper
+        earlyWarningDelay = Math.min(PaperConfig.watchdogPrintEarlyWarningDelay, timeoutTime); // Paper
     }
 
     private static long monotonicMillis()
@@ -56,10 +63,18 @@ public class WatchdogThread extends Thread
     {
         while ( !stopping )
         {
-            //
-            if ( lastTick != 0 && monotonicMillis() > lastTick + timeoutTime && !Boolean.getBoolean("disable.watchdog")) // Paper - Add property to disable
+            // Paper start
+            Logger log = Bukkit.getServer().getLogger();
+            long currentTime = monotonicMillis();
+            if ( lastTick != 0 && currentTime > lastTick + earlyWarningEvery && !Boolean.getBoolean("disable.watchdog") )
             {
-                Logger log = Bukkit.getServer().getLogger();
+                boolean isLongTimeout = currentTime > lastTick + timeoutTime;
+                // Don't spam early warning dumps
+                if ( !isLongTimeout && (earlyWarningEvery <= 0 || !hasStarted || currentTime < lastEarlyWarning + earlyWarningEvery || currentTime < lastTick + earlyWarningDelay)) continue;
+                if ( !isLongTimeout && MinecraftServer.getServer().hasStopped()) continue; // Don't spam early watchdog warnings during shutdown, we'll come back to this...
+                lastEarlyWarning = currentTime;
+                if (isLongTimeout) {
+                // Paper end
                 log.log( Level.SEVERE, "------------------------------" );
                 log.log( Level.SEVERE, "The server has stopped responding! This is (probably) not a Paper bug." ); // Paper
                 log.log( Level.SEVERE, "If you see a plugin in the Server thread dump below, then please report it to that author" );
@@ -89,29 +104,46 @@ public class WatchdogThread extends Thread
                     }
                 }
                 // Paper end
+                } else
+                {
+                    log.log(Level.SEVERE, "--- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH  - " + Bukkit.getServer().getVersion() + " ---");
+                    log.log(Level.SEVERE, "The server has not responded for " + (currentTime - lastTick) / 1000 + " seconds! Creating thread dump");
+                }
+                // Paper end - Different message for short timeout
                 log.log( Level.SEVERE, "------------------------------" );
                 log.log( Level.SEVERE, "Server thread dump (Look for plugins here before reporting to Paper!):" ); // Paper
                 dumpThread( ManagementFactory.getThreadMXBean().getThreadInfo( MinecraftServer.getServer().serverThread.getId(), Integer.MAX_VALUE ), log );
                 log.log( Level.SEVERE, "------------------------------" );
                 //
+                // Paper start - Only print full dump on long timeouts
+                if ( isLongTimeout )
+                {
                 log.log( Level.SEVERE, "Entire Thread Dump:" );
                 ThreadInfo[] threads = ManagementFactory.getThreadMXBean().dumpAllThreads( true, true );
                 for ( ThreadInfo thread : threads )
                 {
                     dumpThread( thread, log );
                 }
+                } else {
+                    log.log(Level.SEVERE, "--- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH ---");
+                }
+
+
                 log.log( Level.SEVERE, "------------------------------" );
 
+                if ( isLongTimeout )
+                {
                 if ( restart && !MinecraftServer.getServer().hasStopped() )
                 {
                     RestartCommand.restart();
                 }
                 break;
+                } // Paper end
             }
 
             try
             {
-                sleep( 10000 );
+                sleep( 1000 ); // Paper - Reduce check time to every second instead of every ten seconds, more consistent and allows for short timeout
             } catch ( InterruptedException ex )
             {
                 interrupt();
-- 
2.24.1