Santiago,
thanks for confirming our observation.
Currently, we get all user data and the user PSMLs from IBM Secure Way
Directory Server (pretty scalable). Our traces/logs were switched off
during the performance measurements.
We are currently analyzing the trace staments across the JetSpeed code in
detail, maybe we'll find a piece of code that sequentializes all the
servlet threads.
Best regards,
Thomas
Thomas Schaeck
IBM Pervasive Computing Division
Phone: +49-(0)7031-16-3479 Mobile: +49-(0)171-6928407 e-mail:
[EMAIL PROTECTED] Fax: +49-(0)7031-16-4888
Address: IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032
Boeblingen, Germany
[EMAIL PROTECTED] escribió:
>
> We have done some performance measurements, running JetSpeed on RS/6000
> machines with one and with four processors. The 4-way machine's
processors
> are running about twice as fast as the 1-way's. Surprisingly, performance
> seems to increase proportionally with the speed of the processors, but
> seems not to improve with the number of processors. Did anybody observe
> similar behavior ?
Yes. I observed similar behaviour under 2-way with Linux Sun jdk 1.3
Server Hotspot.
In my tests, response time grows about 50% between 1 and 2 concurrent
requests. From there on, response time growm linearly with the number of
concurrent requests. With "perfect" concurrency, time should be the same
between 1 and 2 concurrent requests.
>
> A potential explanation for this behavior might be synchronized
statements
> in code that is called directly or indirectly from the service-method of
a
> servlet. Are there known problems in this area ?
>
I have not identified any such execution path. Potential problem areas
are the factories and other singletons, where look up must be performed
for components ( getPortlet(), ...) and also the database (I'm using
Hypersonic for my tests).
Which DB are you using?
The logging is a big potential bottleneck, since the threads fight to
get a lock on the logger stream. We are logging maybe 20 lines (=20
locks) per request.
Do you have profiling data? The profiler does not work under linux
hotspot :(
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