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From Michael Smith <>
Subject Re: Tomcat memory management
Date Tue, 12 Nov 2002 01:02:27 GMT
Scott Johnson wrote:
> Hello,
> We've got an application that is replicated for clients, each
> replication runs in its own context. We're running jdk1.4.1, RH7.2,
> Tomcat 4.0.6
> Even though the application itself can run fine on 10mb RAM, as each
> context initializes, EVERY thread allocates more memory until we get
> 20-30 contexts up with each context taking 60-90mb RAM:
> An example process output will have one entry like this for every
> context:
> root      2900  0.0  6.6 257624 68556 pts/1  S    18:32   0:00
> /usr/java/jdk1.4.1_01/bin/java -Xmx10m
> -Djava.endorsed.dirs=/usr/java/tomcat/bin:/usr/java/tomcat/common/lib
> -classpath
> /usr/java/jdk1.4.1_01/lib/tools.jar:/usr/java/tomcat/bin/bootstrap.jar -
> As you can see, the -Xmx... argument is of no effect as these processes
> are taking 68mb.
> For us the optimal solution would be to have a single process handling
> all of the contexts, or have each context limited to 10mb.
> I've searched for a configuration to allow the former, and the Xmx arg
> isn't working on the latter. Does anyone have any ideas?

Under linux, the distinction between threads and processes is fairly
small - and ps doesn't (in that version) display threads differently.

What you _actually_ have here are threads - but only a single process.
The memory usage you see on each of these threads is actually shared
across all of the threads for that JVM (the JVM is a single process). So
this isn't really a problem - you have 70 megs (or whatever) used _in
total_ by the JVM, across 20-30 threads. 


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