[teiid-issues] [JBoss JIRA] (TEIID-3106) BufferManager Cleaner consuming 90% of total CPU time

[Steven Hawkins (JIRA)]

    [ https://issues.jboss.org/browse/TEIID-3106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12999556#comment-12999556 ] 

Steven Hawkins commented on TEIID-3106:
---------------------------------------

Ok, there is another commit.  I believe another possible issue was when the persistent flag was set, which could cause an issue in that the insertion into the secondary queue will modify the key while the entry is still in the initial queue.

> BufferManager Cleaner consuming 90% of total CPU time
> -----------------------------------------------------
>
>                 Key: TEIID-3106
>                 URL: https://issues.jboss.org/browse/TEIID-3106
>             Project: Teiid
>          Issue Type: Bug
>          Components: Query Engine
>    Affects Versions: 8.7
>         Environment: zOS
>            Reporter: Devesh Mishra
>            Assignee: Steven Hawkins
>              Labels: teiid-engine
>         Attachments: BufferManagerImpl.java, BufferManagerImpl.java, CacheKey_Loog.patch, complete_log.zip, cpu monitoring.docx, dump.zip, in_local.docx, LrfuEvictionQueue.java, LrfuEvictionQueue.patch, non_high_cpu.docx
>
>
>  BufferManager Cleaner thread is consuming almost all of the CPU utilized by the jboss process. Thread dump shows following information.
> 3XMTHREADINFO      "BufferManager Cleaner" J9VMThread:0x0000004C41CFEB00, j9thread_t:0x0000004C52B85AE0, java/lang/Thread:0x000000481C036E20, state:CW, prio=5
> 3XMJAVALTHREAD            (java/lang/Thread getId:0x76, isDaemon:true)
> 3XMTHREADINFO1            (native thread ID:0x3AEC2600, native priority:0x5, native policy:UNKNOWN)
> 3XMHEAPALLOC             Heap bytes allocated since last GC cycle=2609184 (0x27D020)
> 3XMTHREADINFO3           Java callstack:
> 4XESTACKTRACE                at java/util/concurrent/ConcurrentSkipListMap.doRemove(ConcurrentSkipListMap.java:1070(Compiled Code))
> 4XESTACKTRACE                at java/util/concurrent/ConcurrentSkipListMap.remove(ConcurrentSkipListMap.java:1659(Compiled Code))
> 4XESTACKTRACE                at org/teiid/common/buffer/impl/LrfuEvictionQueue.remove(LrfuEvictionQueue.java:60(Compiled Code))
> 4XESTACKTRACE                at org/teiid/common/buffer/impl/BufferManagerImpl.doEvictions(BufferManagerImpl.java:854(Compiled Code))
> 5XESTACKTRACE                   (entered lock: org/teiid/common/buffer/CacheEntry at 0x00000048393C2598, entry count: 1)
> 4XESTACKTRACE                at org/teiid/common/buffer/impl/BufferManagerImpl$Cleaner.run(BufferManagerImpl.java:108)
> 4XESTACKTRACE                at java/util/TimerThread.mainLoop(Timer.java:555)
> 4XESTACKTRACE                at java/util/TimerThread.run(Timer.java:505)
> When we added log statements around the BufferManagerImpl.doEvictions() it loops through the remove and firstEntry loop. 
> Forum discussion link : https://community.jboss.org/message/901792



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