Java Help - Tomcat out of memory

Author

Tomcat out of memory

Dale

2004-09-27, 4:02 pm

I've a situation where Tomcat is crashing with an out of memory error
every 24-48 hours. I think I may have narrowed down the cause: we have
tens of thousands of jsp pages, and every time one of them is compiled
i see the heap size grow, and it never shrinks back down. Eventually
Tomcat becomes unresponsive, writes out of memory to the catalina log,
and I have to restart it. Here's what I'm running:

RedHat Linux ES 3.0
Apache 2.0.46 with ( mod_jk )
Tomcat 4.1.24
Sun j2sdk 1.4.2_03

My question is, I've explicitly set it in the web.xml configuration so
that Tomcat forks javac processes to another memory partition. Even
so, I'm seeing out of memory reported by Tomcat. Is this a memory leak
in javac, Ant, or is my original hypothesis incorrect?

thanks,
Dale

William Brogden

2004-09-27, 4:02 pm

On 27 Sep 2004 10:51:00 -0700, Dale <dalelum@gmail.com> wrote:

> I've a situation where Tomcat is crashing with an out of memory error
> every 24-48 hours. I think I may have narrowed down the cause: we have
> tens of thousands of jsp pages, and every time one of them is compiled
> i see the heap size grow, and it never shrinks back down. Eventually
> Tomcat becomes unresponsive, writes out of memory to the catalina log,
> and I have to restart it. Here's what I'm running:
>
> RedHat Linux ES 3.0
> apache 2.0.46 with ( mod_jk )
> Tomcat 4.1.24
> Sun j2sdk 1.4.2_03
>
> My question is, I've explicitly set it in the web.xml configuration so
> that Tomcat forks javac processes to another memory partition. Even
> so, I'm seeing out of memory reported by Tomcat. Is this a memory leak
> in javac, Ant, or is my original hypothesis incorrect?
>
> thanks,
> Dale

Tomcat 5 release notes contain this:
-quote-
--------------------
JAVAC leaking memory:
--------------------

The Java compiler leaks memory each time a class is compiled. Web
applications
containing hundreds of JSP files may as a result trigger out of memory
errors
once a significant number of pages have been accessed. The memory can only
be
freed by stopping Tomcat and then restarting it.

The JSP command line compiler (JSPC) can also be used to precompile the
JSPs.

Note: This issue has been fixed in Sun JDK 1.4.x.
-endquote-

Bill

Dale Lum

2004-09-27, 4:02 pm

> Tomcat 5 release notes contain this:
> -quote-
> --------------------
> JAVAC leaking memory:
> --------------------
>
> The Java compiler leaks memory each time a class is compiled. Web
> applications
> containing hundreds of JSP files may as a result trigger out of memory
> errors
> once a significant number of pages have been accessed. The memory can
> only be
> freed by stopping Tomcat and then restarting it.
>
> The JSP command line compiler (JSPC) can also be used to precompile the
> JSPs.
>
> Note: This issue has been fixed in Sun JDK 1.4.x.
> -endquote-

Yes, I've read that. I am running the 1.4.2 JDK. I've also set javac to
fork. The Tomcat docs have this to say about that:

fork - The internal JVM javac compiler used by Ant has a known memory
leak. And Ant requires that java compiles be synchronized, i.e. only one
JSP page can be compiled at a time. Set fork to true or do not define it
(it is the default value) so that Ant compiles JSP pages in a seperate
JVM. This removes the synchronization of JSP page compiles and prevents
all the javac classes from being instantiated and subsequently garbage
collected by the JVM Tomcat is running in. This also works around known
issues with javac, including memory leaking, as well as JAR file locking
on Windows.

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