Very short application run time and stops

[James Nichols]

I was just running some workload through an application on a test
environment.  For some reason, I had a run of very short application run
times and pauses, as shown in this GC snippet.  The young generation and old
generation both had low occupancy rates right before this occurred.  After
this log output, the next GC showed Eden at 99% full, which was then
collected in under a second.    I'm kinda perplexed as to what is going on
when this occurred as there isn't any GC related information output during
this time.  When the workload began against the application a bunch of
threads became active doing work, but I don't believe they were creating
excessive amounts of garbage.


Total time for which application threads were stopped: 0.2914130 seconds
Application time: 2.0577050 seconds
Total time for which application threads were stopped: 0.0234770 seconds
Application time: 0.0021460 seconds
Total time for which application threads were stopped: 0.0316840 seconds
Application time: 0.0016000 seconds
Total time for which application threads were stopped: 0.0218700 seconds
Application time: 0.1401370 seconds
Total time for which application threads were stopped: 0.0401360 seconds
Application time: 0.0007750 seconds
Total time for which application threads were stopped: 0.0235050 seconds
Application time: 0.0018830 seconds
Total time for which application threads were stopped: 0.0327830 seconds
Application time: 0.0010240 seconds
Total time for which application threads were stopped: 0.0218930 seconds
Application time: 0.0008780 seconds
Total time for which application threads were stopped: 0.0375390 seconds
Application time: 0.0006810 seconds
Total time for which application threads were stopped: 0.0212840 seconds
Application time: 0.0010380 seconds
Total time for which application threads were stopped: 0.0314600 seconds
Application time: 0.0007640 seconds


Attached is the zipped up GC log.  Here are my GC arguments:

/usr/java/jdk1.5.0_12/bin/java -Dprogram.name=run.sh -server -Xms4096m
-Xmx4096m -XX:NewSize=1228M -XX:MaxNewSize=1228M -XX:MaxTenuringThreshold=4
-XX:SurvivorRatio=6 -XX:+ScavengeBeforeFullGC -XX:PermSize=256M
-XX:MaxPermSize=256M -XX:+HandlePromotionFailure -XX:+UseConcMarkSweepGC
-XX:+UseParNewGC -XX:ParallelGCThreads=3 -XX:+CMSParallelRemarkEnabled
-XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled -verbosegc
-XX:+DisableExplicitGC -XX:+PrintTenuringDistribution -XX:+PrintGCDetails
-XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC
-XX:+PrintGCApplicationConcurrentTime -XX:+PrintGCApplicationStoppedTime
-XX:+PrintClassHistogram -Xloggc:/var/log/jboss/gc.dat
-Dsun.net.client.defaultConnectTimeout=10000
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