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

[Jesper Wilhelmsson]

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.

/Jesper