RFR (S) 8072693: [BACKOUT] GCCause should distinguish jcmd GC.run from System.gc()

Mikael Gerdin mikael.gerdin at oracle.com
Wed Feb 11 14:08:41 UTC 2015



On 2015-02-11 11:30, Jesper Wilhelmsson wrote:
> Kim Barrett skrev den 11/2/15 00:03:
>> On Feb 6, 2015, at 10:10 AM, Mikael Gerdin <mikael.gerdin at oracle.com>
>> wrote:
>>>
>>> Hi all,
>>>
>>> There are some problems with the Diagnostic Command GCCause change, I
>>> suggest that we back out the change and reconsider its implementation.
>>>
>>> [from the bug]
>>> The change is incomplete since several places in the GC code assumes
>>> that explicit gcs have the _java_lang_system_gc GCCause value in
>>> order to determine the behavior.
>>> For example:
>>> ParallelGC does not apply policy decisions on user-invoked GCs
>>> (decided by the GCCause)
>>> G1/CMS honors +ExplicitGCInvokesConcurrent based on the GCCause setting.
>>> This could cause problems for people expecting concurrent gcs when
>>> running the diagnostic command instead of a possibly several-second
>>> full gc pause.
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8072693
>>> Webrev: http://cr.openjdk.java.net/~mgerdin/8072693/webrev.0/
>>
>> A procedural question: Shouldn't this backout be accompanied by
>> re-opening the original RFE (JDK-8068589) that was resolved by the
>> changeset that is now being backed out?
>>
>
> We can't reopen the old issue since it has already been used to push a
> change. The procedure is to create a REDO issue by cloning the original
> issue. I have done that now.

Right, I was planning to do that but I forgot about it. Thanks Kim for 
pointing that out and Jesper for fixing it.

/Mikael

>
> /Jesper


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