It's not a secret anymore!
The moose likes Tomcat and the fly likes Any Memory Usage Limitation for Tomcat 5 or 6? Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Products » Tomcat
Bookmark "Any Memory Usage Limitation for Tomcat 5 or 6?" Watch "Any Memory Usage Limitation for Tomcat 5 or 6?" New topic

Any Memory Usage Limitation for Tomcat 5 or 6?

Ashik Uzzaman
Ranch Hand

Joined: Jul 05, 2001
Posts: 2373

Is their any built in memory usage limitation for Tomcat 5? For example, we can add a JAVA_OPTS and specify -Xms and -Xmx to tell the JVM the maximum memory space that can be used. But if I have 8 GB RAM in my server and I tell Xms to be 4 GB and Xmx to be 8 GB to Tomcat 5, will it be able to utilize 8 GB memory if required? Is there a limitation around it for Tomcat 5 (like maximum 2 GB will be used)? And for Tomcat 6? I tried to find the answer in tomcat documentation without success.

Your comments will be appreciated.

Ashik Uzzaman
Senior Software Engineer, TubeMogul, Emeryville, CA, USA.
Marco Ehrentreich
best scout

Joined: Mar 07, 2007
Posts: 1294

Hi Ashik,

the amount of memory Tomcat can use mainly depends on the JVM and OS. If you want to use multiple GBs of RAM you will have to use a 64 bit OS/JVM. Then you can set the catalina options for Tomcat to higher values than the default for 32 bit JVMs (which is depending on the OS ~ 1,5 GB).

Kees Jan Koster
JavaMonitor Support

Joined: Mar 31, 2009
Posts: 251
For more detail of the limitations of 32-bit systems, and a graphic of how the memory is laid out:

Kees Jan

Java-monitor, JVM monitoring made easy <- right here on Java Ranch
Misha Ver
Ranch Hand

Joined: Mar 03, 2008
Posts: 470
Ashik, keep in mind that a larger heap will cause garbage collection pauses to increase because there is more heap to scan
I agree. Here's the link:
subject: Any Memory Usage Limitation for Tomcat 5 or 6?
It's not a secret anymore!