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

[Sergey Bylokhov]

Hi, Alexander.

Can you please run the same test using the minimum possible Xmx(like 5 
or 10 mb). It will be interesting who the performance will drop will be 
in this corner case, when the memory is under pressure.

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.