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Suppose someone is using a 64-bit OS and a 64-bit JVM.

Does using the 64-bit Tomcat increase performance?

This may seem a little stange, however someone suggested that the 64-bit Tomcat basically, only had a different installer. This seems wrong to me, but I don't really have any proof.

Is there some doc about this?

I mean can the 64bit tomcat reach more RAM, than the 32-bit version?

GC_
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4 Answers4

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Tomcat is a Java application. There isn't a 32 and 64 bit version, unless you are talking about any native extentions such as APR.

cherouvim
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    So all Java applications are automatically 64 bit, with a 64-bit JVM? – GC_ Jan 12 '11 at 20:36
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    Yes. The application is being run by the JVM. If the JVM is 64bit then it's supposed to do some things faster and hopefully your application will benefit. – cherouvim Jan 12 '11 at 20:37
  • Do you know of any documentation that says something like that? I would like to read more about this. However, I think I believe that is true. – GC_ Jan 13 '11 at 13:55
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You can access more RAM, which may help performance, yes, but that depends on your application, e.g. if it actually does need more than the approx 1.5Gb a 32 bit JVM can handle.

Be wary though, you might see occasional performance degradation as garbage collection has more to clean up!

Brian
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Regarding performance. You might want to look at this answer.

Regarding RAM - yes, 32 bit Java apps (Tomcat included) can only use up to ~1.4G. If you need more, use 64 bit JVM.

Community
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mindas
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  • True or false? It does not matter which verison of Tomcat I use, 64bit or 32bit. It only matters which JVM I use, 32bit verses 64bit. – GC_ Jan 13 '11 at 13:51
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    True. I think you have been mislead because you have seen different downloadables for Windows platform. None of the Tomcat Java code is different, it's just Windows service launchers that are different. – mindas Jan 13 '11 at 14:49
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The question is performance and not if the application can use more memory.

The main point is the JVM used. As mentioned, the JAVA primary data object are 64bits. It will be more efficient to run Tomcat and JVM 64 bits if the CPU of the host is natively 64 bits. In 32 bits, calculating a 64bit value will require more cpu cycles than doing the equivalent operation on a 64bits native system. Same is true for string object and manipulation. The operation work on 4 bytes at a time instead of 2.

So, in summary, it is more efficient to run Tomcat and the underplaying JVM on 64bits.

Tkx.

Luc Major
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