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From "Strecker, Mark" <>
Subject RE: -Xincgc, -Xms600, -Xmx600
Date Mon, 02 Jun 2003 18:23:41 GMT

>>I question whether this is a memory issue. Even if you use 600MB, why
>>tomcat run at 100% cpu forever??? Shouldn't the gc finish???

>GC may finish and immediately restart if memory is still full.  That
>would keep CPU usage pegged.

Sure, it is possible that the gc could run as long as your process is running, but it should
stop after your process completes. If tomcat keeps running at 100% cpu forever, you have a
problem ... something that looks like an infinite loop.

>>I am using jdk1.3.1_07. I know that people upgraded to jdk1.4 and the
>>problem persists ... so it's probably not a JVM issue.

>I don't think that's a possible conclusion without significant further
>investigation.  There are simply too many variables, too many difference
>between JDK 1.3.x and 1.4.x, and "people" vs your specific situation.

All I'm saying is, just upgrading the VM is a waste of time. If it's a VM issue it's not fixed
yet ... or it's been reintroduced. Maybe the answer is to do what Hua Hou suggested, upgrade
to 1.4.1_02 and replace the setLength() method with the 1.3.1_07 version.

>Can you see if it's actually GC that's using the CPU?  If not, what is?
>One way to find out is to ctrl-break your tomcat when it's using 100%
>CPU.  You will get output showing what exactly every thread in the VM
>was doing.

I would like to know this too ... actually any information about what it is doing would be
great. I tried to attach the MS debugger ... but had problems doing so on NT. Now that I have
a W2K installation too, I will try again.

How do I ctrl-break a service ... or make it dump this information?


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