RFR: 8008917 CMS: Concurrent mode failure tracing event

Erik Helin erik.helin at oracle.com
Wed Mar 6 10:19:09 PST 2013


Hi Kevin,

I think that there _might_ be a bug in CMS which was present even before 
you added the event tracing.

If you look in aquire_control_and_collect, you will see that 
"should_compact" can be set to false by 
decide_foreground_collection_type. If this is the case, then we will end 
up in do_mark_sweep_work.

The problem is that you have already reported, and CMS has already 
printed, that a concurrent mode failure has occurred in 
acquire_control_and_collect. Then, when you enter do_mark_sweep_work, 
you will once again report, and CMS will again print, that concurrent 
mode failure has happened.

I am not 100% sure that I am right, by I believe that this can happen.

What do you think?

Thanks,
Erik

On 03/01/2013 06:34 PM, Kevin Walls wrote:
> Hi,
>
> I'd like some reviews on this CMS Concurrent Mode Failure event:
>
> http://cr.openjdk.java.net/~kevinw/8008917/hotspot/
>
> The event doesn't actually carry any new information, but it is a
> warning we need to capture.
>
> This is against hsx24, I'll prepare the same, or reviewed, changes
> against very latest hotspot also.
>
> Thanks
> Kevin
>



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