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

[Pavel]

Ricardo,

I did not test the issue on different app servers and databases. However,
underlying reasons for this "out of memory" make me strongly believe that
changing DB/AS will make little or no difference.

Pavel

On Feb 17, 2008 12:09 AM, [Ricardo Rodriguez] Your EPEC Network ICT Team <
webmaster at environmentalchange.net> wrote:

> Pavel wrote:
> > 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
>
> Hi Pavel,
>
> Do you know if this heap size issue happens just working with Tomcat as
> servlet container or it is generalizable to other application servers?
> It could be advisable clarify that this FAQ applies just to XWiki
> running on a Tomcat/MySQL server.
>
> I would add a link to "heap", something as
> http://dictionary.zdnet.com/definition/heap.html. I am not a programmer,
> so I do need this kind of help to know what is happening with my
> installation :-)
>
> As per the CATALINA_OPTS or JAVA_OPTS variables, it would be great to
> have a confirmation, but by tracking their values along catalina.sh and
> startup.sh I reach the same conclusion you presented. FAQs are wiki
> entries, so anybody can modify them! I would add some
> sample lines as (this apply to Unix-based systems, could you add that
> applying to Windows ones?)...
>
> * to be included in a script calling startup.sh: both variables will be
> passed in to the startup process.
>
> export CATALINA_OPTS="-Xmx512m -Xms512m"
> export JAVA_OPTS="-Xmx512m -Xms512m"
>
> I am guessing it is of course possible to add this values within
> catanina.sh or startup.sh, but I do prefer don't touch these files if
> possible.
>
> Cheers,
>
> Ricardo
>
>
> --
> Ricardo Rodríguez
> Your EPEC Network ICT Team
>
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> http://lists.xwiki.org/mailman/listinfo/users
>



-- 
Best regards,
Pavel
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