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From Lindsay Patten <>
Subject Re: 100% cpu usage by "VM Thread" in tomcat
Date Fri, 21 Sep 2007 20:23:48 GMT
Looking at the cpu times, top says that pid 324 has used over 900 
minutes of cpu time, none of the other tomcat threads have used more 
than 9 minutes.  When the system is grinding it is pid 324 that is 
listed as 97% of cpu with no other java threads on screen.  The problem 
may be caused by something in my code but the cpu activity appears to be 
taking place in that system thread. Garbage collection seems to be the 
most obvious candidate. I'm not sure where to go with that conclusion, I 
received a reference to GCViewer, but I need to figure out how to 
reproduce the situation out of the production server to see how I can 
use it...

Further suggestions very welcome!


Caldarale, Charles R wrote:
>> From: Lindsay Patten [] 
>> Subject: 100% cpu usage by "VM Thread" in tomcat
>> Expecting to find that I had some error in my webapp I did a 
>> few thread dumps, but assuming that nid in the thread dump
>> corresponds to pid from ps I found that the process that was
>> spinning was "VM Thread":
>> "VM Thread" prio=1 tid=0x08098a48 nid=0x144 runnable
> That's not likely to be the one actually spinning, unless your JVM is
> very broken.  The VM thread will always show as runnable, since it's the
> one displaying the thread dump.  You probably need to look a bit more
> closely at the other threads.

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