<Swing Dev> [9] Review request for 8132791 No access to SynthContext.getContext()

[Sergey Bylokhov]

On 13.04.16 22:14, Alexander Scherbatiy wrote:
>    The tests immediately fail with OOME using -Xmx2m option, fail on the
> same steps with 3 and 4 mb and pass with 5 mb.

And there is no difference in SwingMark results before and after the fix?

>
> Thanks,
> Alexandr.
>
>>
>> On 12.04.16 22:02, Alexander Scherbatiy wrote:
>>>
>>> Hello,
>>>
>>> Could you review the fix:
>>>    bug: https://bugs.openjdk.java.net/browse/JDK-8132791
>>>    webrev: http://cr.openjdk.java.net/~alexsch/8132791/webrev.00
>>>
>>>
>>> SynthContext is an object with 4 fields which is used a lot by Synth L&F
>>> for components painting. It has an internal API which allows to put
>>> unused objects to queue and reuse them later. Application developers
>>> will not be able to have access to this API in JDK 9 with modularization
>>> feature so they only be able to create new SyntContext objects. There
>>> are ways that a SyntContext object created by a developer can be
>>> disposed by Synth L&F and put to the unused object queue. This can lead
>>> to a memory leak.
>>>
>>> There are 2 options to fix the issue: provide a public API for the
>>> SyntContext object custom disposing or just get rid of the unused object
>>> queue.
>>>
>>> Effective Java Guide has a suggestion: “avoiding object creation by
>>> maintaining your own object pool is a bad idea unless the objects in the
>>> pool are extremely heavyweight”
>>>
>>> To check if there are memory or performance degradation for the second
>>> solution I used SwingMark application which extensively creates and
>>> paints a lot of Swing components like labels, menus and others.
>>>
>>> The tests were run 5 times with using the object queue and without it.
>>> There results can be found at:
>>> http://cr.openjdk.java.net/~alexsch/8132791/profiling/results_3-5
>>>
>>> The minimum and maximum values from 5 runs are:
>>>
>>> Tests which used an object queue:
>>> used memory (in bytes)
>>>    min: 3.75 million max: 3.78 million
>>> heap size  (in bytes)
>>>    min: 11.53 million max: 12.58 million
>>> elapsed time (in milliseconds)
>>>    min: 57.27 thousand max: 57.97 thousand
>>> requests for SynthContext objects: 380 thousands
>>> created objects: 21
>>>
>>> Tests which did not use an object queue:
>>> used memory (in bytes)
>>>    min:  3.71 million max: 3.79 million
>>> heap size   (in bytes)
>>>    min: 11.53 million max: 12.58 million
>>> elapsed time (in milliseconds)
>>>    min: 57.90 thousand max: 57.97 thousand
>>> requests for SynthContext objects: 380 thousands
>>> created objects: 380 thousands
>>>
>>> There were about 380 thousand request for SynthContext objects in both
>>> tests but only 21 object were crated for the first ones.
>>>
>>> However, the used memory size and running time are nearly the same for
>>> both runs for these particular tests.
>>>
>>> According to the test results it looks reasonable to remove the custom
>>> object pool support from the SynthContext object.
>>>
>>> Thanks,
>>> Alexandr.
>>>
>>
>>
>


-- 
Best regards, Sergey.