RFR(xs): 8134749: SoftReferences declared dead too early
jon.masamitsu at oracle.com
Mon Aug 31 18:20:58 UTC 2015
Change looks good.
Could you please run some tests with your fix and
-XX:+UseParallelGC threads? UseDynamicNumberOfGCThreads sometimes moves
work among the queues to get them into queues that will be processed by
GC worker. Thanks.
On 08/31/2015 07:15 AM, Per Liden wrote:
> While preparing a different patch I looked through the
> ReferenceProcessor and noticed what looks like a silent mistreatment
> of SoftReferences.
> Summary: RefProcPhase1Task uses WorkerThread::id() to select the list
> to process. After the recent changes to how WorkGang works, this no
> longer guarantees that all reference lists are processed. This in turn
> means we might kill SoftReferences even when the policy says they
> should be kept alive.
> The fix here would be to use the worker_id (named "i" in this code)
> passed into the Task's work() function instead of using
>  There's no longer any guarantee that all GangWorker threads will
> execute the Task's work() function, since a quick-to-wakeup worker
> thread might steal the work intended for a slow-to-wakeup worker thread.
> Webrev: http://cr.openjdk.java.net/~pliden/8134749/webrev.0/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8134749
> Testing: jprt
> Btw, I'll to send out a follow-up patch (JDK-8134744) which makes sure
> WorkerThread::id() and the worker_id always match to avoid this type
> of bugs in the future.
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