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Re: Memory allocation jump after running for a while with a largenumber of threads

Hrvoje Niksic wrote:
[...] The problem is that, from time to time, memory usage suddenly jumps by a huge amount, say by a gigabyte. So the application with 3000 threads that used to consume ~800M memory suddenly consumes ~1800M!

This reminds me of the well-known memory strangenesses of Java.

Strangeness in general, or do you have something specific in mind?

The periodic burps caused by the GC, say. Us C programmers will blame all your suddent memory consumption jumps on that without even looking at the evidence :-)

Have you also tracked number of outstanding connections? Any correlation?

Have you checked the Java community for suggestions?

I've done a fair amount of google searching, but nothing relevant has shown up. I didn't know of a more narrow community where this might be relevant.

Try maybe http://forum.java.sun.com/forum.jsp?forum=37 or maybe http://www-106.ibm.com/developerworks/forums/dw_forum.jsp?forum=176&cat=10 ?

You might also consider writing a minimal test case to demonstrate
it. (Hard, I know.)

I'll try that as a last resort, but I don't expect much success. For this effect to show, the chat server must sometimes run for days. Without insight into exactly what triggers the jump, it might be very hard to come up with code that reproduces it reliably.

Yep. One other suggestion: have you tried various JVM's? If it happens with, say, IBM's as well, then you have some hope it's the OS. Likewise, any chance you can run this app on another OS? - Dan

-- Dan Kegel http://www.kegel.com http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045

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