RFR(L) 8153224 Monitor deflation prolong safepoints (CR3/v2.03/6-for-jdk13)

[Daniel D. Daugherty]

Greetings,

I had some discussions with Karen about a race that was in the
ObjectMonitor::enter() code in CR2/v2.02/5-for-jdk13. This race was
theoretical and I had no test failures due to it. The fix is pretty
simple: remove the special case code for async deflation in the
ObjectMonitor::enter() function and rely solely on the ref_count
for ObjectMonitor::enter() protection.

During those discussions Karen also floated the idea of using the
ref_count field instead of the contentions field for the Async
Monitor Deflation protocol. I decided to go ahead and code up that
change and I have run it through the usual stress and Mach5 testing
with no issues. It's also known as v2.03 (for those for with the
patches) and as webrev/6-for-jdk13 (for those with webrev URLs).
Sorry for all the names...

Main bug URL:

     JDK-8153224 Monitor deflation prolong safepoints
     https://bugs.openjdk.java.net/browse/JDK-8153224

The project is currently baselined on jdk-13+18.

Here's the full webrev URL:

http://cr.openjdk.java.net/~dcubed/8153224-webrev/6-for-jdk13.full/

Here's the incremental webrev URL:

http://cr.openjdk.java.net/~dcubed/8153224-webrev/6-for-jdk13.inc/

I have also updated the OpenJDK wiki to reflect the CR3 changes:

https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation

This version of the patch has been thru Mach5 tier[1-8] testing on
Oracle's usual set of platforms. My Solaris-X64 stress kit run had
no issues. Kitchensink8H on product, fastdebug, and slowdebug bits
had no failures on Linux-X64; MacOSX fastdebug and slowdebug and
Solaris-X64 release had the usual "Too large time diff" complaints.
12 hour Inflate2 runs on product, fastdebug and slowdebug bits on
Linux-X64, MacOSX and Solaris-X64 had no failures. My Linux-X64
stress kit is running right now.

I've done the SPECjbb2015 baseline and CR3 runs. I need to gather
the results and analyze them.

Thanks, in advance, for any questions, comments or suggestions.

Dan


On 4/25/19 12:38 PM, Daniel D. Daugherty wrote:
> Greetings,
>
> I have a small but important bug fix for the Async Monitor Deflation
> project ready to go. It's also known as v2.02 (for those for with the
> patches) and as webrev/5-for-jdk13 (for those with webrev URLs). Sorry
> for all the names...
>
> JDK-8222295 was pushed to jdk/jdk two days ago so that baseline patch
> is out of our hair.
>
> Main bug URL:
>
>     JDK-8153224 Monitor deflation prolong safepoints
>     https://bugs.openjdk.java.net/browse/JDK-8153224
>
> The project is currently baselined on jdk-13+17.
>
> Here's the full webrev URL:
>
> http://cr.openjdk.java.net/~dcubed/8153224-webrev/5-for-jdk13.full/
>
> Here's the incremental webrev URL (JDK-8153224):
>
> http://cr.openjdk.java.net/~dcubed/8153224-webrev/5-for-jdk13.inc/
>
> I still have to update the OpenJDK wiki to reflect the CR2 changes:
>
> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>
> This version of the patch has been thru Mach5 tier[1-6] testing on
> Oracle's usual set of platforms. Mach5 tier[7-8] is running now.
> My stress kit is running on Solaris-X64 now. Kitchensink8H is running
> now on product, fastdebug, and slowdebug bits on Linux-X64, MacOSX
> and Solaris-X64. 12 hour Inflate2 runs are running now on product,
> fastdebug and slowdebug bits on Linux-X64, MacOSX and Solaris-X64.
> I'll start my my stress kit on Linux-X64 sometime on Sunday (after
> my jdk-13+18 stress run is done).
>
> I'll do SPECjbb2015 baseline and CR2 runs after all the stress
> testing is done.
>
> Thanks, in advance, for any questions, comments or suggestions.
>
> Dan
>
>
> On 4/19/19 11:58 AM, Daniel D. Daugherty wrote:
>> Greetings,
>>
>> I finally have CR1 for the Async Monitor Deflation project ready to
>> go. It's also known as v2.01 (for those for with the patches) and as
>> webrev/4-for-jdk13 (for those with webrev URLs). Sorry for all the
>> names...
>>
>> Main bug URL:
>>
>>     JDK-8153224 Monitor deflation prolong safepoints
>>     https://bugs.openjdk.java.net/browse/JDK-8153224
>>
>> Baseline bug fixes URL:
>>
>>     JDK-8222295 more baseline cleanups from Async Monitor Deflation 
>> project
>>     https://bugs.openjdk.java.net/browse/JDK-8222295
>>
>> The project is currently baselined on jdk-13+15.
>>
>> Here's the webrev for the latest baseline changes (JDK-8222295):
>>
>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/4-for-jdk13.8222295
>>
>> Here's the full webrev URL (JDK-8153224 only):
>>
>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/4-for-jdk13.full/
>>
>> Here's the incremental webrev URL (JDK-8153224):
>>
>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/4-for-jdk13.inc/
>>
>> So I'm looking for reviews for both JDK-8222295 and the latest version
>> of JDK-8153224...
>>
>> I still have to update the OpenJDK wiki to reflect the CR changes:
>>
>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>
>> This version of the patch has been thru Mach5 tier[1-3] testing on
>> Oracle's usual set of platforms. Mach5 tier[4-6] is running now and
>> Mach5 tier[78] will be run later today. My stress kit on Solaris-X64
>> is running now. Linux-X64 stress testing will start on Sunday. I'm
>> planning to do Kitchensink runs, SPECjbb2015 runs and my monitor
>> inflation stress tests on Linux-X64, MacOSX and Solaris-X64.
>>
>> Thanks, in advance, for any questions, comments or suggestions.
>>
>> Dan
>>
>>
>> On 3/24/19 9:57 AM, Daniel D. Daugherty wrote:
>>> Greetings,
>>>
>>> Welcome to the OpenJDK review thread for my port of Carsten's work on:
>>>
>>>     JDK-8153224 Monitor deflation prolong safepoints
>>>     https://bugs.openjdk.java.net/browse/JDK-8153224
>>>
>>> Here's a link to the OpenJDK wiki that describes my port:
>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>>
>>> Here's the webrev URL:
>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/3-for-jdk13/
>>>
>>> Here's a link to Carsten's original webrev:
>>>
>>> http://cr.openjdk.java.net/~cvarming/monitor_deflate_conc/0/
>>>
>>> Earlier versions of this patch have been through several rounds of
>>> preliminary review. Many thanks to Carsten, Coleen, Robbin, and
>>> Roman for their preliminary code review comments. A very special
>>> thanks to Robbin and Roman for building and testing the patch in
>>> their own environments (including specJBB2015).
>>>
>>> This version of the patch has been thru Mach5 tier[1-8] testing on
>>> Oracle's usual set of platforms. Earlier versions have been run
>>> through my stress kit on my Linux-X64 and Solaris-X64 servers
>>> (product, fastdebug, slowdebug).Earlier versions have run Kitchensink
>>> for 12 hours on MacOSX, Linux-X64 and Solaris-X64 (product, fastdebug
>>> and slowdebug). Earlier versions have run my monitor inflation stress
>>> tests for 12 hours on MacOSX, Linux-X64 and Solaris-X64 (product,
>>> fastdebug and slowdebug).
>>>
>>> All of the testing done on earlier versions will be redone on the
>>> latest version of the patch.
>>>
>>> Thanks, in advance, for any questions, comments or suggestions.
>>>
>>> Dan
>>>
>>> P.S.
>>> One subtest in gc/g1/humongousObjects/TestHumongousClassLoader.java
>>> is currently failing in -Xcomp mode on Win* only. I've been trying
>>> to characterize/analyze this failure for more than a week now. At
>>> this point I'm convinced that Async Monitor Deflation is aggravating
>>> an existing bug. However, I plan to have a better handle on that
>>> failure before these bits are pushed to the jdk/jdk repo.
>>>
>>
>>
>
>