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From Mark Washeim <>
Subject Re: load related problem
Date Mon, 10 Jul 2000 20:28:48 GMT
on 10/7/00 6:52 pm, Mark Washeim at wrote:

> on 10/7/00 5:31 am, Donald Ball at wrote:
>>> Mark Washeim wrote:
>>>> I've been load testing an xsp application (one of the eurofootball apps)
>>>> and
>>>> am having difficulty determining the origin of this exception:
>>>> java.lang.NullPointerException
>>>> at org.apache.cocoon.processor.xsp.XSPUtil.cloneNode(Compiled Code)
>>>> at org.apache.cocoon.processor.xsp.XSPUtil.cloneNode(Compiled Code)
>>>> at org.apache.cocoon.processor.xsp.XSPUtil.cloneNode(Compiled Code)
>>>> at org.apache.cocoon.processor.xsp.XSPPage.xspExpr(Compiled Code)
>>>> at
>>>> _opt._IBMHTTPD._htdocs._en_US._editorial._gb_home.populateDocument(Compiled
>>>> Code)
>>>> it only occurs when I bring the load up to about 40 to 50 concurrent
>>>> requests (per second).
>>> Interesting thorughput :o)
>>>> I'm wondering if it's because the method within the xsp:expr isn't
>>>> returning
>>>> (which shouldn't happen and doesn't under less load) or whether it's
>>>> something else?
>>>> Any ideas ?
>>> One might wonder if some OutOfMemoryError has been caught and ignored...
>> one might also check and see if the library method being invoked by
>> xsp:expr is the cause of the null pointer by simply forking 40-50 threads
>> and repeatedly call it from them. my gut says that xsp is the problem, but
>> it'd be good to eliminate the external possibilities first. other likely
>> candidate is the jvm.
>> - donald

For those of you who are macintosh fans, you'll be pleased with this:

I can't reproduce the outOfMemory error related problems I get when testing
on Solaris (an Enterprise 250 machine with 2 processors and 1 GB of RAM) . .
. It's amazing. 

The mac I tested on is a G4 with 256 mb of ram. Tomcat 3.1 used as the
servlet engine (and webserver).

Even running 30 or 40 concurrent threads, XSPUtil.cloneNode kept on

It's so wierd that a deficient virtual memory scheme like the mac's could
deal with this. 

Mark (Poetaster) Washeim

'On the linen wrappings of certain mummified remains
found near the Etrurian coast are invaluable writings
that await translation.

Quem colorem habet sapientia?'

Evan S. Connell


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