[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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Steven Hawkins commented on TEIID-3106:
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The failure of my theory is that I can't find where
ConcurrentSkipListMap uses equals() when comparing keys.
It shouldn't, unless there is something different about the implementation in your vm.
As it stands hashcode/equals are consistent, which is a requirement. compareTo however
isn't required to be consistent with equals, only that when !a.equals(b) &&
a.compareTo(b) == 0 will there likely be issues. In this case we can have a.equals(b)
&& a.compareTo(b) != 0
I'd have to double check, but we should just directly use the id when holding the
cache entries in maps otherwise, so you should be able to locally just change the
implementation of equals if you want to test that out.
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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