RFR: Backport of 6412968 and 6990419 to 7u

Poonam Bajaj poonam.bajaj at oracle.com
Thu Feb 13 16:23:52 PST 2014


Hi Ramki,

On 2/13/2014 2:30 PM, Srinivas Ramakrishna wrote:
> Hi Poonam --
>
> Awesome, thanks for doing the backport (and thanks to Yasumasa for the 
> original fixes)!  Are there performance numbers to share? 
> (Unfortunately the original jira's aren't publicly visible on openjdk, 
> in case performance data is attached there.)
>
There are no performance numbers attached to the JIRA bug reports.

However, this problem was seen with 7uxx too and here's the logs showing 
this issue:

/  [1 CMS-initial-mark: 144994K(360640K)] 277255K(508096K), 1.8159856 
secs] /
/Times: user=1.86 sys=0.00, real=1.82 secs] /
/[1 CMS-initial-mark: 128606K(360832K)] 261393K(508288K), 1.8203566 secs] /
/[Times: user=1.86 sys=0.01, real=1.82 secs] /

Logs after backporting only '6412968 
<https://bugs.openjdk.java.net/browse/JDK-6412968>: CMS: Long initial 
mark pauses' :

/ 2014-01-29T15:57:05.638+0100: 20626.412: [GC (Survivor:87chunks) 
Finished /
/young gen initial mark scan work in 17th thread: 0.001 sec/
/Finished young gen initial mark scan work in 4th thread: 0.001 sec/
/Finished young gen initial mark scan work in 1th thread: 0.001 sec/
/Finished young gen initial mark scan work in 3th thread: 0.001 sec/
/Finished young gen initial mark scan work in 11th thread: 0.001 sec/
/Finished young gen initial mark scan work in 6th thread: 0.001 sec/
/Finished young gen initial mark scan work in 8th thread: 0.001 sec/
/Finished young gen initial mark scan work in 18th thread: 0.001 sec/
/Finished young gen initial mark scan work in 7th thread: 0.001 sec/
/Finished young gen initial mark scan work in 23th thread: 0.000 sec/
/Finished young gen initial mark scan work in 24th thread: 0.000 sec/
/Finished young gen initial mark scan work in 2th thread: 0.001 sec/
/Finished young gen initial mark scan work in 0th thread: 0.001 sec/
/Finished young gen initial mark scan work in 5th thread: 0.001 sec/
/Finished young gen initial mark scan work in 22th thread: 0.001 sec/
/Finished young gen initial mark scan work in 10th thread: 0.001 sec/
/Finished young gen initial mark scan work in 21th thread: 0.001 sec/
/Finished young gen initial mark scan work in 20th thread: 0.001 sec/
/Finished young gen initial mark scan work in 19th thread: 0.001 sec/
/Finished young gen initial mark scan work in 14th thread: 0.001 sec/
/Finished young gen initial mark scan work in 13th thread: 0.001 sec/
/Finished young gen initial mark scan work in 16th thread: 0.001 sec/
/Finished young gen initial mark scan work in 9th thread: 0.001 sec/
/Finished young gen initial mark scan work in 12th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 0th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 12th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 21th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 23th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 10th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 6th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 5th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 11th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 24th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 17th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 13th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 7th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 16th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 20th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 3th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 8th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 4th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 9th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 1th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 2th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 22th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 19th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 14th thread: 0.006 sec/
/Finished remaining root initial mark scan work in 18th thread: 0.006 sec/
/Finished young gen initial mark scan work in 15th thread: 1.814 sec/
/Finished remaining root initial mark scan work in 15th thread: 0.000 sec/
/  [1 CMS-initial-mark: 128606K(360832K)] 261393K(508288K), 1.8203566 
secs] /
/[Times: user=1.86 sys=0.01, real=1.82 secs]/
/2014-01-29T15:57:07.459+0100: 20628.232: Total time for which 
application /
/threads were stopped: 1.8363302 seconds

/Work distribution is skewed./

/Logs after backporting '6990419 
<https://bugs.openjdk.java.net/browse/JDK-6990419>: CMS: Remaining work 
for 6572569: consistently skewed work distribution in (long) re-mark 
pauses' as well:

/ 2014-02-05T18:56:54.070+0100: 7130.738: [GC (Survivor:47chunks) 
Finished /
/young gen initial mark scan work in 3th thread: 0.085 sec/
/Finished young gen initial mark scan work in 16th thread: 0.084 sec/
/Finished young gen initial mark scan work in 8th thread: 0.085 sec/
/Finished young gen initial mark scan work in 17th thread: 0.085 sec/
/Finished young gen initial mark scan work in 0th thread: 0.085 sec/
/Finished young gen initial mark scan work in 12th thread: 0.085 sec/
/Finished young gen initial mark scan work in 13th thread: 0.085 sec/
/Finished young gen initial mark scan work in 1th thread: 0.086 sec/
/Finished young gen initial mark scan work in 9th thread: 0.085 sec/
/Finished young gen initial mark scan work in 4th thread: 0.086 sec/
/Finished young gen initial mark scan work in 20th thread: 0.085 sec/
/Finished young gen initial mark scan work in 22th thread: 0.085 sec/
/Finished remaining root initial mark scan work in 8th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 17th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 0th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 13th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 12th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 16th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 20th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 22th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 1th thread: 0.001 sec/
/Finished young gen initial mark scan work in 6th thread: 0.086 sec/
/Finished remaining root initial mark scan work in 4th thread: 0.001 sec/
/Finished remaining root initial mark scan work in 6th thread: 0.000 sec/
/Finished young gen initial mark scan work in 11th thread: 0.086 sec/
/Finished remaining root initial mark scan work in 11th thread: 0.000 sec/
/Finished young gen initial mark scan work in 5th thread: 0.087 sec/
/Finished remaining root initial mark scan work in 5th thread: 0.000 sec/
/Finished young gen initial mark scan work in 21th thread: 0.086 sec/
/Finished remaining root initial mark scan work in 21th thread: 0.000 sec/
/Finished young gen initial mark scan work in 14th thread: 0.087 sec/
/Finished remaining root initial mark scan work in 14th thread: 0.000 sec/
/Finished young gen initial mark scan work in 10th thread: 0.087 sec/
/Finished young gen initial mark scan work in 19th thread: 0.087 sec/
/Finished remaining root initial mark scan work in 10th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 19th thread: 0.000 sec/
/Finished young gen initial mark scan work in 23th thread: 0.087 sec/
/Finished remaining root initial mark scan work in 23th thread: 0.000 sec/
/Finished young gen initial mark scan work in 2th thread: 0.088 sec/
/Finished remaining root initial mark scan work in 2th thread: 0.000 sec/
/Finished young gen initial mark scan work in 7th thread: 0.088 sec/
/Finished young gen initial mark scan work in 24th thread: 0.087 sec/
/Finished remaining root initial mark scan work in 7th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 24th thread: 0.000 sec/
/Finished young gen initial mark scan work in 18th thread: 0.087 sec/
/Finished remaining root initial mark scan work in 18th thread: 0.000 sec/
/Finished young gen initial mark scan work in 15th thread: 0.089 sec/
/Finished remaining root initial mark scan work in 15th thread: 0.000 sec/
/Finished remaining root initial mark scan work in 3th thread: 0.006 sec/
/Finished remaining root initial mark scan work in 9th thread: 0.006 sec/
/  [1 CMS-initial-mark: 157005K(360832K)] 291355K(508288K), 0.0967082 
secs] /
/[Times: user=2.18 sys=0.01, real=0.10 secs]/
/2014-02-05T18:56:54.167+0100: 7130.835: Total time for which application /
/threads were stopped: 0.1116541 seconds

/
> Which version of 7u is this slated to make an appearance?
Not sure as of now. Will try for 7u60.

Thanks,
Poonam

>
> thanks!
> -- ramki
>
>
>
> On Wed, Feb 12, 2014 at 6:14 PM, Poonam Bajaj <poonam.bajaj at oracle.com 
> <mailto:poonam.bajaj at oracle.com>> wrote:
>
>     Hi,
>
>     Could I have some reviews on the following backport changes, please.
>     http://cr.openjdk.java.net/~poonam/6412968_6990419/webrev.01/
>     <http://cr.openjdk.java.net/%7Epoonam/6412968_6990419/webrev.01/>
>
>     Thanks,
>     Poonam
>
>
>     On 2/11/2014 10:30 AM, Poonam Bajaj wrote:
>>     Hi,
>>
>>     As per Jon Masamitsu's suggestion, we would be having the
>>     CMSParallelInitialMarkEnabled and CMSEdenChunksRecordAlways
>>     flags' value 'false' by default for 7u so as not to introduce any
>>     behavior changes in 7 update release. The updated webrev is here:
>>     http://cr.openjdk.java.net/~poonam/6412968_6990419/webrev.01/
>>     <http://cr.openjdk.java.net/%7Epoonam/6412968_6990419/webrev.01/>
>>
>>     Thanks,
>>     Poonam
>>
>>     On 2/9/2014 5:13 PM, Poonam Bajaj wrote:
>>>     Hi All,
>>>
>>>     Could I have some reviews for the backport of the following two
>>>     fixes from jdk8 to 7u:
>>>     6412968 <https://bugs.openjdk.java.net/browse/JDK-6412968>: CMS:
>>>     Long initial mark pauses
>>>     6990419 <https://bugs.openjdk.java.net/browse/JDK-6990419>: CMS:
>>>     Remaining work for 6572569: consistently skewed work
>>>     distribution in (long) re-mark pauses
>>>
>>>     These changes parallelize the initial-mark phase of the CMS
>>>     collector and improve the work distribution among parallel
>>>     worker threads.
>>>     Webrev:
>>>     http://cr.openjdk.java.net/~poonam/6412968_6990419/webrev.00/
>>>     <http://cr.openjdk.java.net/%7Epoonam/6412968_6990419/webrev.00/>
>>>
>>>     Original fixes:
>>>     6412968 :
>>>     http://hg.openjdk.java.net/hsx/hsx25/hotspot/rev/ca9dedeebdec
>>>     6990419:
>>>     http://hg.openjdk.java.net/hsx/hsx25/hotspot/rev/7b06ae405d7b
>>>
>>>     Testing:
>>>     JPRT, Customer verification testing
>>>
>>>     Thanks,
>>>     Poonam
>>>
>>>
>>>
>
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