16 Feb
2008
16 Feb
'08
9:58 p.m.
Here is my version of what happens in Q&A.
* What does out of memory error mean?
- Java virtual machine (which runs tomcat which runs xwiki) has run out of
heap space and cannot allocate anything anymore.
* Is it related to MySQL packet size?
- No
* Why this error happens?
- Because application needs more memory than JMV is allowed to use.
* How is that related to attachments?
- The way xwiki handles attachments is, well, not perfect.
Somewhat related thread is
http://lists.xwiki.org/pipermail/users/2007-November/009362.html
* So what can you do?
- a) Use -Xms and -Xmx java parameters to increase heap size.
- b) Implement and contribute to XWiki effective attachment handling.
* What are the -Xms and -Xmx params?
- -Xms tells java the initial heap size, -Xmx controls max size. The
latter is of special interest in this case and can be increased.
Pavel
On Feb 16, 2008 4:24 PM, <Dowson_Jim(a)emc.com> wrote:
Ricardo Rodriguez wrote:
>Dowson_Jim(a)emc.com wrote:
> An MS Word document.
>
> The error also happened with a 6.5 MB zip file - so the xwiki limit
of
> 10MB may not be the issue (although documents
larger than the alleged
> 1MB MySQL limit have been successfully uploaded).
Thus, the problem may arise from the amount of
memory available for
Java. What servlet container are you using? I've seen this error here
running Tomcat. You can increase this amount by passing this parameter
"-Xmx256m -Xms256m" (in this case 256Mb will be the new amount of
available memory) at startup time.
I'll have to check with the lab folks - I believe they started with the
1.2M2 Windows complete build, then upgraded to 1.2RC2.
I will let you know after I have heard from them.
I wanted to make the changes one step at a time to isolate the root
cause.
So, you have to shutdown your servlet container,
modify some script to
startup.sh, catalina.sh or whatever your are using to launch Tomcat, to
>add this paramenters to CATALINA_OPTS or
JAVA_OPTS. I have not a clear
idea about what is the right variable to be
modified. Any feedback will
be really welcome.
Here is the script I am using here to start
Tomcat:
mire:/home/webmaster/bin # cat start_tomcat6
#!/bin/sh
export CATALINA_HOME=/usr/share/tomcat-6.0.10
export JAVA_HOME=/usr/share/java/jre-1.6.0_01
export JRE_HOME=/usr/share/java/jre-1.6.0_01
export CATALINA_OPTS="-Xmx512m -Xms512m"
export JAVA_OPTS="-Xmx512m -Xms512m"
$CATALINA_HOME/bin/startup.sh
As per your question about the need of restarting
XWiki so that the new
configuration values become effective. Yes, this
is required. xwiki.cfg
is read at deployment time. So if you have any
utility that allow you
to
restart just one application, you are a lucky
person :-) If you have
not
it, just restart the servlet container.
I expected that to be the case - and the FAQ should be updated to
reflect that
(I didn't consider myself as authoritative, so I didn't want to edit the
entry).
I would also suggest that the error code (Java ....) be added to the
text as well.
I am sure there are people out there with a much
more in depth
knowledge
about this issue. But this has helped me. I hope
it could be useful for
you as well.
Perhaps, but by speaking, you're the most effective person ;-)
I'll update you (here) after we apply the changes and test again.
Thanks for your help!
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