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From "Robin Green" <gree...@hotmail.com>
Subject Re: Out of Memory Error
Date Sun, 19 Nov 2000 22:46:31 GMT
Alex Muc <alex.muc@utoronto.ca> wrote:
>I've been bit recently by the Out of Memory error which some users have
>been reporting when using Cocoon under various setups.  I'd be very
>interested in seeing the problem solved.

Me too.

>  I searched through the
>archives and I didn't find any solutions but if someone knows the answer
>to the problem please tell me about it.

I think it can sometimes be caused by misconfiguration. There is a setting 
in cocoon.properties, which is only documented in cocoon.properties itself, 
which needs to be set to the same value as the maximum heap size, in order 
for the MemoryStore flushing algorithm to work correctly. However, I've just 
now changed the algorithm in CVS so that it works no matter what you set 
that value to (it just flushes more aggressively if you set it to a lower 
value).

>Anyways, in an effort to try and fix this problem I would like to get as
>complete a set of details about all the various platforms that it has
>occurred on a possible.  Hopefully then we can try and track it down.
>So, if anyone who has experienced this problem could spend a couple of
>minutes to fill out the following then we can try and find a solution:
>
>Cocoon version:
>Servlet Container and version:
>JDK version:
>Operating System and version:
>Integeration with Apache:
>Running time before failure:
>Number of requests before failure:
>Uses JDBC:
>JDBC Driver and version and level:
>Other description:

What about the most important thing - maximum heap size allowed for the JVM? 
The JVM picks its own default maximum based on the amount of RAM in the 
machine, unless you specify it with the -Xmx or -mx command-line option.

You can probably find what the default is by looking at the amount of memory 
allocated for Java in top or kps under Unix, or the Task Manager under 
NT/2000, after a lot of requests have been processed and the memory usage 
stabilises. I don't know how to find it out under Win95/98. Cocoon shouldn't 
actually _need_ much memory - a lot of it will be just cache that can be 
flushed, I would think.

>Based on my experience with the problem and the tests that I've done it
>seems like it is a problem with the servlet container but I don't know
>for sure.

What makes you say that?

>
>Anyways, the following is the description for my system:
>Cocoon version: 1.8
>Servlet Container and version: Jakarta-tomcat 3.1 final
>JDK version:  Sun 1.2.2
>Operating System and version: Win98
>Integeration with Apache: via mod_jserv
>Running time before failure: 12 hours
>Number of requests before failure: 1.5 million
>Uses JDBC: yes
>JDBC Driver and version and category:  MM_mysql Driver, 1.1b, Category 4
>Other description: The problem only ever appeared after I was doing some
>stress testing on my web app.  Using the JMeter test harness is when the
>problem first appeared.  Most of my XSP pages are pretty short.  They do
>draw information out a database but that info gets cached after the
>first access so actual database usage is pretty minimal.

What we really need is someone who can reproduce the problem and run a 
memory profiling tool over Cocoon, like JProbe. Even the built-in Java 
profiler(s) might generate useful information. I tried once but didn't get 
very far.



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