RFR(XXS): 8034775: Failing to initialize VM when running with negative value for -XX:CICompilerCount (original) (raw)

Vladimir Kozlov vladimir.kozlov at oracle.com
Thu Feb 13 22:55:04 PST 2014

On 2/13/14 9:52 PM, Albert wrote:

Hi Vladimir, thanks for looking at this.

Why would you limit the number of compiler threads to os::activeprocessorcount()? It intuitively makes sense However, if for whatever reason, a customer wants more compiler threads than processors there is no reason to not let him do that.

I don't want an other bug when someone can run with ridiculously high number. You need a lot compiler threads only during startup when you need to compile a lot but you need to give some resources to application and GC.

On other hand we don't have limit for ParallelGCThreads. So we may not need it too. Okay.

Yes, tiered works with -XX:CICompilerCount=1. In that case we silently start 2 compiler threads, which seems to contradict -XX:CICompilerCount=1. void AdvancedThresholdPolicy::initialize() { .. setc1count(MAX2(count / 3, 1)); setc2count(MAX2(count - count / 3, 1)); .. }

Okay, then setting default 2 for Tiered is fine.

Do you know why this flag is called CICompilerCount and not CICompilerThreads? Would you say it makes sense to change the flag so that it is possible to set the number of C1/C2 compiler threads? _product(ccstr, CICompilerCount, NULL, _ _"Read compiler commands from this file [.hotspotcompiler]") _

I don't know why it is named such. Unfortunately we can't change it - a lot of people know and use this flag.

This version of the test should be fine. http://cr.openjdk.java.net/~anoll/8034775/webrev.01/

Looks good.

Thanks, Vladimir

Best, Albert On 02/13/2014 05:34 PM, Vladimir Kozlov wrote: Albert,

Can you also check upper limit: os::activeprocessorcount()? Tiered works when CICompilerCount=1. Can you look what is difference in such case from CICompilerCount=2? The test expects "at least 2" but for Client VM and non-Tiered it is 1. So your test will fail. Thanks, Vladimir On 2/13/14 2:54 AM, Albert wrote: Hi,

could I get reviews for this small patch? bug: https://bugs.openjdk.java.net/browse/JDK-8034775 webrev: http://cr.openjdk.java.net/~anoll/8034775/webrev.00/ With this patch, we check at VM startup for a reasonable minimal number of compiler threads (1 for non-tiered, and 2 for tiered). If this minimum is not reached, the VM exits. Added regression test. Many thanks, Albert

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