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From "Marco Laponder" <>
Subject RE: unexpected high cpu load
Date Tue, 23 Mar 2010 06:53:21 GMT
I have create a jira for this issue

Kind regards,

-----Oorspronkelijk bericht-----
Van: Kevan Miller [] 
Verzonden: maandag 22 maart 2010 21:05
Onderwerp: Re: unexpected high cpu load

On Mar 22, 2010, at 2:56 PM, Marco Laponder wrote:

> Hi,
> I am experiencing,while running my web application, a very high load
> the system where Geronimo is running (4 cpu's are busy). 
> I tried to find the cause of the problem by sending a kill -3 and
> inspecting the java vm thread dump. I attached it to this mail but I
> couldn't detect the cause of the problem of the CPU usage. 
> A number of threads are in the containsKey on the hashmap triggered by
> the getResource on the MultiParentClassLoader which strikes me as odd,
> can this be the source of the problem ? 
> Are there other ways to determine why the CPU is load is this heavy?
> tips are appreciated. 

One simple test is to create several thread dumps and compare the two.
Java profiling tools, java debugger, logging, etc. (in no particular
order) are additional techniques...

Looking at your thread dump, I see 4 threads in
NavigatorTalkbackMgr.getMessage() doing a wait() (I assume they have a
relatively long or infinite wait time) and 4 threads in
MultiParentClassLoader.getResource(). The getResource calls definitely
look suspicious... 

I'll bet a beverage of choice that there's been a concurrent read/write
on the resourcesNotFound HashMap, the write thread caused the HashMap to
be resized, and the read threads are now stuck in an infinite loop in
HashMap.containsKey(). MultiParentClassLoader.getResource() is
definitely wrong and needs to prevent concurrent access to the
resourcesNotFound HashMap.

Please create a Jira -- patches are also welcome! :)


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