RFR: 8244297: Provide utility for testing for memory leaks [v6]

[Florian Kirmaier]

On Wed, 7 Oct 2020 12:09:15 GMT, Ambarish Rapte <arapte at openjdk.org> wrote:

>> Florian Kirmaier has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   JDK-8244297
>>   Fixed unit-test
>
> modules/javafx.base/src/test/java/test/util/memory/JMemoryBuddy.java line 132:
> 
>> 130:      * Checks whether the content of the WeakReference can not be collected.
>> 131:      * @param weakReference The WeakReference to check.
>> 132:      * @return Returns true, when the provided WeakReference can be collected.
> 
> needs typo correction: can not be collected

done

> modules/javafx.base/src/test/java/test/util/memory/JMemoryBuddy.java line 152:
> 
>> 150:         f.accept(new MemoryTestAPI() {
>> 151:             public void assertCollectable(Object ref) {
>> 152:                 if(ref == null) throw new NullPointerException();
> 
> `Object.requireNonNull()` method would be more suitable choice for null check.

done

> modules/javafx.base/src/test/java/test/util/memory/JMemoryBuddy.java line 113:
> 
>> 111:         if(weakReference.get() == null && counter < steps / 3) {
>> 112:             int percentageUsed = (int) ((steps - counter) / steps * 100);
>> 113:             System.out.println("Warning test seems to be unstable. time used: " + percentageUsed + "%");
> 
> Seems like candidate for `System.err.`

That might be true, but honestly, I'm using System.err so rarely (never) that I have a better feeling avoiding it altogether and eliminating the chance for rare cornercases.

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PR: https://git.openjdk.java.net/jfx/pull/204