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From Dennis Dai <>
Subject Re: JVM memory size changing dramatically
Date Wed, 28 Jul 2004 19:36:55 GMT
Can't remember where I read it but it's something like this on 
NT/2k/XP/2k3 family:

Windows is using the physical memory as cache to cache the real app 
image in the swap file. So if your app has been idle for a while, it's 
very likely to be swap out of the physical memory. This is regardless of 
how much physical memory you have.

Interesting approach but sometimes annoying.

On 7/28/2004 9:11 AM, Futchi wrote:

> Hi all,
>             I am running tomcat 5 on Win2003 server, my single app. has
> several threads running in the background (threads loading and writing
> data, detecting URL connections).
> Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in the
> Tasks Manager, it keeps running stable and getting up and down between
> 80 and 93 MB memory size. After several hours, memory size gets down to
> 5 MB very fast, and then start goes up to 90 MB also fast.   This change
> happening in about 2-3 minutes only, then it becomes stable again
> jumping between 80-93 MB memory size.
> While this happening Tomcat is up and running, also my App. is up and
> running. I do not have any memory error messages.
> I doubt it is the GC, Anybody can explain that?!!!
> My JAVA_OPTS as follows
> JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m
> -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5
> -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k
> -XX:+DisableExplicitGC

Dennis Dai

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