topic RHEL3 SMP java CPU-hog in Operating System - Linux

RHEL3 SMP java CPU-hog

Timo J — Tue, 12 Apr 2005 01:58:49 GMT

- 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.

Re: RHEL3 SMP java CPU-hog

Stuart Browne — Tue, 12 Apr 2005 02:11:11 GMT

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..

Re: RHEL3 SMP java CPU-hog

Timo J — Tue, 12 Apr 2005 02:30:05 GMT

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)

Re: RHEL3 SMP java CPU-hog

Stuart Browne — Tue, 12 Apr 2005 04:18:12 GMT

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

Is hyperthreading 'ON' on the other system?

Re: RHEL3 SMP java CPU-hog

Timo J — Tue, 12 Apr 2005 04:20:33 GMT

Yes, hyperthreading is ON on both systems.

Re: RHEL3 SMP java CPU-hog

Stuart Browne — Tue, 12 Apr 2005 04:32:45 GMT

Odd..

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

Sorry..

Re: RHEL3 SMP java CPU-hog

Timo J — Tue, 12 Apr 2005 05:16:49 GMT

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.