[teiid-issues] [JBoss JIRA] (TEIID-3106) BufferManager Cleaner consuming 90% of total CPU time
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https://issues.jboss.org/browse/TEIID-3106?page=com.atlassian.jira.plugin...
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Mark Addleman commented on TEIID-3106:
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I'll take a wild stab at the problem: I don't believe that the compareTo()
definition is consistent with equals(). It appears that under some conditions equals()
can return true where compareTo() does not return 0. I can't create a complete story
out of this yet, but I believe this inconsistency ends up driving
ConcurrentSkipListMap.doRemove() mad as it tries to find the key to remove. The failure
of my theory is that I can't find where ConcurrentSkipListMap uses equals() when
comparing keys.
I'm only mentioning it now because it seems to fit the profiling results that Devesh
provided and on the off chance it gives you some insight into what's going on.
BufferManager Cleaner consuming 90% of total CPU time
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Key: TEIID-3106
URL: https://issues.jboss.org/browse/TEIID-3106
Project: Teiid
Issue Type: Bug
Security Level: Public(Everyone can see)
Components: Query Engine
Affects Versions: 8.7
Environment: zOS
Reporter: Devesh Mishra
Assignee: Steven Hawkins
Labels: teiid-engine
Attachments: BufferManagerImpl.java, CacheKey_Loog.patch, cpu monitoring.docx,
in_local.docx, 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@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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