[jira] [Commented] (AMQ-6482) Possible thread leak ?

["Maxence Dunnewind (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AMQ-6482?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15609200#comment-15609200 ] 

Maxence Dunnewind commented on AMQ-6482:
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This keeps increasing , ~ 400 thread every 4/5 hours. Right now, on the same instance :

   1873  (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
   1613  (a java.util.concurrent.locks.ReentrantLock$NonfairSync)


> Possible thread leak ?
> ----------------------
>
>                 Key: AMQ-6482
>                 URL: https://issues.apache.org/jira/browse/AMQ-6482
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 5.14.1
>            Reporter: Maxence Dunnewind
>              Labels: threading
>         Attachments: thread_dump
>
>
> We have an activemq broker running for ~ 24 hours, handling ~ 100k topics and up to 8k connections (for ~ 24k consumers).
> Looking at my graph, I see that I get a big increase of threads count happended (in 4 steps, ~ 500 more threads each time) as shown here : https://snapshot.raintank.io/dashboard/snapshot/ExUb4pgNYnmBo92JgbZrvJ6fiBm3PNrI
> However, even if the traffic dropped in the night, the thread count never decreased and is still ~ 2500.
> I checked a thread dump and it looks like (full dump attached) :
> ```
> # grep  Thread.State thread_dump   |awk '{ print $2 }' |sort|uniq -c
>      26 RUNNABLE
>      70 TIMED_WAITING
>    2446 WAITING
> ```
> Mhh, so many WAITING threads, let's check why :
> ```
> # grep   'parking to' thread_dump    |cut -d '>' -f 2 |sort |uniq -c
>       1  (a java.util.concurrent.CountDownLatch$Sync)
>    1308  (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
>    1159  (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
>      41  (a java.util.concurrent.SynchronousQueue$TransferStack)
> ```
> I'm not a big java expert but seems a bit unexpected behavior to me.
> For various reason (big number of topics etc ) we use custom GC config, here it is :
> ```
> ACTIVEMQ_OPTS_MEMORY="-Xms128M -Xmx10G -Xloggc:/home/log/activemq/gc.log -XX:+PrintGC -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+UseG1GC -XX:InitiatingHeapOccupancyPercent=75 -XX:NewRatio=4"
> ```
> Maxence



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