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From "Will Hartung" <>
Subject Re: Cache & CPU utilisation problems on Tomcat 5.5.7 on Windows 2003
Date Tue, 24 May 2005 02:25:37 GMT
> From: "Andrew Stevens" <>
> Sent: Monday, May 23, 2005 6:43 PM

> 1. Cache -

Can't help here, sorry...

> 2. CPU utilisation - Tomcat often hits 99% CPU and just stays there
> until the server just comes to a grinding halt. This could of course be
> a coding issue in a JSP or what have you, but my error logs are not
> pointing to anything unusual.

What do your GC stats look like? (-verbose:gc) Is TC out of memory and
fighting itself? Even worse, is Tomcat swapping? (Java no like swapping, no
sir. Bad. Really Bad.) Remember that your Java will allocate more memory
than what you may specify on the command line, that only limits the heap
size for the JVM, not how much Java takes overall.

I've had Tomcat when hammered go into a thrashing spin lock on Solaris, this
was 4.1.x, though. It was rare, we only caught it once, and it was obviously
fighting among itself for some locks. That wasn't pretty. But it eventually
sorted itself out. No idea what caused it, and I can't consistently
duplicate it.


Will Hartung

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