[GitHub] [geode] dschneider-pivotal commented on a diff in pull request #7751: GEODE-8977: change ThreadMonitor to reduce how long it does a "stop the world" ThreadDump vm op

[GitBox <gi...@apache.org>]

dschneider-pivotal commented on code in PR #7751:
URL: https://github.com/apache/geode/pull/7751#discussion_r890412658


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geode-core/src/main/java/org/apache/geode/internal/monitoring/ThreadsMonitoringProcess.java:
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@@ -119,29 +119,69 @@ private int checkForStuckThreads(Collection<AbstractExecutor> executors, long cu
     return result;
   }
 
+  /**
+   * If set to true, then the JVM will be asked for what locks a thread holds.
+   * This is extra expensive to ask for on some JVMs so be careful setting this to true.
+   */
+  private static final boolean SHOW_LOCKS = Boolean.getBoolean("gemfire.threadmonitor.showLocks");
+  /**
+   * If set to true, then the JVM will be asked for all potential stuck threads with one call.
+   * Since getThreadInfo on many JVMs, stops ALL threads from running, and since getting info
+   * on multiple threads with one call is additional work, setting this can cause an extra long
+   * stop the world that can then cause other problems (like a forced disconnect).
+   * So be careful setting this to true.
+   */
+  private static final boolean BATCH_CALLS = Boolean.getBoolean("gemfire.threadmonitor.batchCalls");
+
+  private static Map<Long, ThreadInfo> createThreadInfoMap(Set<Long> stuckThreadIds) {
+    return createThreadInfoMap(stuckThreadIds, SHOW_LOCKS, BATCH_CALLS);
+  }
+
   @VisibleForTesting
-  public static Map<Long, ThreadInfo> createThreadInfoMap(Set<Long> stuckThreadIds) {
-    /*
-     * NOTE: at least some implementations of getThreadInfo(long[], boolean, boolean)
-     * will core dump if the long array contains a duplicate value.
-     * That is why stuckThreadIds is a Set instead of a List.
-     */
+  public static Map<Long, ThreadInfo> createThreadInfoMap(Set<Long> stuckThreadIds,

Review Comment:
   added test coverage



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