[opencms-dev] OpenCms 7.0.5 crashes with high load

Nacho Fernández Orellana nacho.fernandez.orellana at gmail.com
Thu Mar 26 09:11:19 CET 2009

Hi list and Alkacon members.
We are experiencing a crash on our OpenCms 7.0.5 installation when a web is
access by an estimate of 500 users in roughly half an hour. Even considering
this high load, we expected OpenCms to be able to handle this (and more). I
am sure there are webs powered by OpenCms that handle more than 500
concurrent users and succeed.

We use jboss 4.2.3 on linux and oracle 10. The server has enough CPU and
memory, as our tests indicate the server is by himself not stressed.

The problem seems to be the database connections. I've found that Alex Touza
reported the bug #1717 that indicated that OpenCms pool configured with the
"block" option instead of blocking connections crashed the whole
installation when stressed due to possible missuse of synchronization of
methods that deadlocked threads. We implemented his solution and found that
cpu usage decreased but when the 500 users keep using the web it inevitably
times out every time due to blocked threads even when database was capable
of responding.

We are amazed that using a powerful oracle database on a potent machine that
serves other applications much better on much fewer connections we need to
raise the possible open connections to a high number and still find
problems. The systems management wouldn't accept raising connections to a
shared database that handles other applications with 5 connections opened to
beyond 100. Sure that would solve the problem, but it's quite hard to
convince anyone that a database connection can't be used to handle more than
5 users or so at a time when the database engine and the hardware support
much more.

Sorry for the long message. Any help, hints or success cases would be
appreciated, we hope we can "clear" OpenCms' name in terms of performance
and find it was a simple missconfiguration issue with me to blame. Thank you
in advance. Greetings,

Nacho Fernandez
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