[xwiki-users] [Error]: Java heap memory error on adding large attachment

[Pavel]

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 at emc.com> wrote:

> Ricardo Rodriguez wrote:
>
> >>Dowson_Jim at 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!
> _______________________________________________
> users mailing list
> users at xwiki.org
> http://lists.xwiki.org/mailman/listinfo/users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.xwiki.org/pipermail/users/attachments/20080216/8d71dc45/attachment-0001.html