A question about OS, JDK/Java version and Jboss

[Thomas Chang]

Sometimes I am confused by the relationship between OS and JDK version.

Assumed we have an OS of 64-bit LINUX. I install a Jboss 5 on it. What a JDK should I use? A 32-bit? A 64-bit? Or regardless?

[Peter Johnson]

You can run either the 32-bit or 64-bit JDK on a 64-bit OS. This is assuming that you are running on an AMD or Intel EM64T-capable CPU.

Which one should you use? It depends entirely on the apps you deploy. If you apps need lots of heap space, use the 64-bit JVM because you can declare a larger heap size, but be careful - larger heaps mean larger GC pause times.

[Thomas Chang]

Peter Johnson wrote:You can run either the 32-bit or 64-bit JDK on a 64-bit OS. This is assuming that you are running on an AMD or Intel EM64T-capable CPU.

Which one should you use? It depends entirely on the apps you deploy. If you apps need lots of heap space, use the 64-bit JVM because you can declare a larger heap size, but be careful - larger heaps mean larger GC pause times.

"assuming that you are running on an AMD or Intel EM64T-capable CPU"?

I am using 64-bit RedHat LINUX. Is there any difference?

[Peter Johnson]

I think that RedHat also runs on SPARC, not sure if 64-bit SPARC supports 32-bit SPARC apps (or if there is even such a thing).

In general, if you have an off-the-shelf PC with an Intel or AMD CPU, 64-bit RedHat (I assume you mean RedHat Enterprise Linux, and not Fedora) will run 32-bit apps. (Unless you happened to pick up an Itanium PC, but those fairly rare.)