RHEL3 SMP java CPU-hog

[Timo J]

- Proliant DL360 with 2 physical processors
- RHEL3 AS
- Kernel 2.4.21-20EL / 2.4.21-20ELsmp
- Java version 1.4.2_06

When booting system with uniprocessor kernel, everything is ok. But when booting to SMP, java gets 100% from one CPU. Even 'java -version' gets that 100%. In fact it doesn't come back to prompt but stays stucked. Hyperthreading is ON.

[Stuart Browne]

Given the lack of other command-line arguments, I take it that's the JRE running in native mode.

Unfortunately, the JRE 1.4 series doesn't support green threads.. so my only suggestion is to get the newest JRE possible.

If that doesn't work, try getting a version or two older..

[Timo J]

I just checked from another system with exactly same version of Java and same version of SMP-kernel and there wasn't any problems with Java. (DL580 with four physical processors)

[Stuart Browne]

Running the same java code? Now that's odd.

Is hyperthreading 'ON' on the other system?

[Timo J]

Yes, hyperthreading is ON on both systems.

[Stuart Browne]

Odd..

I've only seen behaviour like this when there was a non-thread-happy while loop occupying the processor..

Sorry..

[Timo J]

Updating to Java 1.4.2_08 solved the problem. But I'm still wondering why 1.4.2_06 is working on that four processor system with same kernel. In fact both systems are installed from same kickstart configuration, so there shouldn't be any major differences.