dschneider-pivotal commented on code in PR #7751:
URL: https://github.com/apache/geode/pull/7751#discussion_r890569224
##########
geode-core/src/main/java/org/apache/geode/internal/monitoring/ThreadsMonitoringProcess.java:
##########
@@ -119,30 +120,87 @@ private int
checkForStuckThreads(Collection<AbstractExecutor> executors, long cu
return result;
}
- @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.
- */
+ /**
+ * 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);
+ }
+
+ public static Map<Long, ThreadInfo> createThreadInfoMap(Set<Long>
stuckThreadIds,
+ boolean showLocks, boolean batchCalls) {
+ return createThreadInfoMap(ManagementFactory.getThreadMXBean(),
stuckThreadIds, showLocks,
+ batchCalls);
+ }
+
+ static Map<Long, ThreadInfo> createThreadInfoMap(ThreadMXBean threadMXBean,
+ Set<Long> stuckThreadIds,
+ final boolean showLocks, final boolean batchCalls) {
if (stuckThreadIds.isEmpty()) {
return Collections.emptyMap();
}
+ logger.info(
+ "Obtaining ThreadInfo for {} threads. Configuration: showLocks={}
batchCalls={}. This is an expensive operation for the JVM and on most JVMs
causes all threads to be paused.",
Review Comment:
It has always been true. Between these two messages we are making calls that
ask ALL threads to pause at a safe point. Once they are all paused we then get
the ThreadInfo. If one of those threads has a high TTSP (time to safe point)
then this can cause what looks like a stop the world gc but without any gc
activity. Since what we do between these two log message could cause things
like a forced disconnect I thought it was worth logging. Note that if we have
no suspects of being stuck then we don't log the messages.
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