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.
