Have Watchdog print the full stacktraces when doing a thread dump, fo…

…r easier debugging (neoforged#512)

patches/net/minecraft/server/dedicated/ServerWatchdog.java.patch

@@ -1,6 +1,6 @@
 --- a/net/minecraft/server/dedicated/ServerWatchdog.java
 +++ b/net/minecraft/server/dedicated/ServerWatchdog.java
-@@ -48,7 +_,7 @@
+@@ -48,14 +_,14 @@
                  ThreadMXBean threadmxbean = ManagementFactory.getThreadMXBean();
                  ThreadInfo[] athreadinfo = threadmxbean.dumpAllThreads(true, true);
                  StringBuilder stringbuilder = new StringBuilder();
@@ -9,3 +9,11 @@
 
                  for(ThreadInfo threadinfo : athreadinfo) {
                      if (threadinfo.getThreadId() == this.server.getRunningThread().getId()) {
+                         error.setStackTrace(threadinfo.getStackTrace());
+                     }
+
+-                    stringbuilder.append(threadinfo);
++                    stringbuilder.append(net.neoforged.neoforge.logging.ThreadInfoUtil.getEntireStacktrace(threadinfo));
+                     stringbuilder.append("\n");
+                 }
+

src/main/java/net/neoforged/neoforge/logging/ThreadInfoUtil.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) NeoForged and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.neoforged.neoforge.logging;
+
+import java.lang.management.LockInfo;
+import java.lang.management.MonitorInfo;
+import java.lang.management.ThreadInfo;
+
+public class ThreadInfoUtil {
+
+    public static String getEntireStacktrace(ThreadInfo threadInfo) {
+        StringBuilder sb = new StringBuilder("\"" + threadInfo.getThreadName() + "\"" +
+                (threadInfo.isDaemon() ? " daemon" : "") +
+                " prio=" + threadInfo.getPriority() +
+                " Id=" + threadInfo.getThreadId() + " " +
+                threadInfo.getThreadState());
+
+        if (threadInfo.getLockName() != null) {
+            sb.append(" on ").append(threadInfo.getLockName());
+        }
+
+        if (threadInfo.getLockOwnerName() != null) {
+            sb.append(" owned by \"").append(threadInfo.getLockOwnerName())
+                    .append("\" Id=").append(threadInfo.getLockOwnerId());
+        }
+
+        if (threadInfo.isSuspended()) {
+            sb.append(" (suspended)");
+        }
+
+        if (threadInfo.isInNative()) {
+            sb.append(" (in native)");
+        }
+
+        sb.append('\n');
+
+        StackTraceElement[] stackTraceElements = threadInfo.getStackTrace();
+        for (int i = 0; i < stackTraceElements.length; i++) {
+            StackTraceElement ste = stackTraceElements[i];
+            sb.append("\tat ").append(ste.toString());
+            sb.append('\n');
+            if (i == 0 && threadInfo.getLockInfo() != null) {
+                Thread.State ts = threadInfo.getThreadState();
+                switch (ts) {
+                    case BLOCKED -> {
+                        sb.append("\t-  blocked on ").append(threadInfo.getLockInfo());
+                        sb.append('\n');
+                    }
+                    case WAITING, TIMED_WAITING -> {
+                        sb.append("\t-  waiting on ").append(threadInfo.getLockInfo());
+                        sb.append('\n');
+                    }
+                    default -> {}
+                }
+            }
+
+            for (MonitorInfo mi : threadInfo.getLockedMonitors()) {
+                if (mi.getLockedStackDepth() == i) {
+                    sb.append("\t-  locked ").append(mi);
+                    sb.append('\n');
+                }
+            }
+        }
+
+        LockInfo[] locks = threadInfo.getLockedSynchronizers();
+        if (locks.length > 0) {
+            sb.append("\n\tNumber of locked synchronizers = ").append(locks.length);
+            sb.append('\n');
+            for (LockInfo li : locks) {
+                sb.append("\t- ").append(li);
+                sb.append('\n');
+            }
+        }
+
+        sb.append('\n');
+        return sb.toString();
+    }
+}