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https://issues.apache.org/jira/browse/GEODE-8977?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17550710#comment-17550710
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Darrel Schneider commented on GEODE-8977:
-----------------------------------------
We figured out that getThreadInfo is an expensive VM ThreadDump operation that
on most JVMs is done in a global safepoint. This means that all other threads
are paused (once each of them reaches a safepoint in their execution) and then
the ThreadDump is done. This can cause what appears to be a gc stop the world
collection.
To reduce the amount of time spend doing the ThreadDump operation, by default
geode will not ask for lock/sync info but instead just get the stack trace.
Also by default it will do the ThreadDump op on each stuck thread individually
instead of with a single call that is passed all the thread ids. This reduces
the amount of time spent in the op and on Java 15 and later it uses a
thread-local safepoint instead of a global safepoint.
To get locks set the system property "gemfire.threadmonitor.showLocks" to
"true".
To get ThreadInfo on all stuck threads with a single call set the system
property "gemfire.threadmonitor.batchCalls" to "true".
> Thread monitoring service should also show locked monitors and synchronizers
> ----------------------------------------------------------------------------
>
> Key: GEODE-8977
> URL: https://issues.apache.org/jira/browse/GEODE-8977
> Project: Geode
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.15.0
> Reporter: Darrel Schneider
> Assignee: Darrel Schneider
> Priority: Major
> Labels: GeodeOperationAPI, blocks-1.15.0, pull-request-available
> Fix For: 1.15.0, 1.16.0
>
>
> The thread monitoring service shows the call stack of a hung thread but it
> does not show the synchronizations obtained by the frames in the call stack
> like a normal stack dump does.
> It looks like this is available from the ThreadInfo class that the service is
> already using by calling getLockedMonitors and getLockedSynchronizers. The
> getLockedMonitors returns a MonitorInfo which has information in it about
> which frame of the stack obtained it. MonitorInfo subclasses LockInfo which
> is what getLockedSynchronizers returns so it is possible that
> getLockedSynchronizers does not provide any additional information to be
> logged.
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