RFR: 8272756: Remove unnecessary explicit initialization of volatile variables in java.desktop
Сергей Цыпанов
github.com+10835776+stsypanov at openjdk.java.net
Tue Sep 21 11:44:49 UTC 2021
On Mon, 20 Sep 2021 11:55:43 GMT, Andrey Turbanov <github.com+741251+turbanoff at openjdk.org> wrote:
>> This is a continuation of
>>
>> - https://bugs.openjdk.java.net/browse/JDK-6736490
>> - https://bugs.openjdk.java.net/browse/JDK-8035284
>> - https://bugs.openjdk.java.net/browse/JDK-8145680
>> - https://bugs.openjdk.java.net/browse/JDK-8251548
>>
>> As mentioned in JDK-6736490:
>>
>> _An explicit initialization of a volatile class instance variable, such as private volatile Object = null; or private volatile int scale = 0; is unnecessary since the Java spec automatically initializes objects to null and primitive type short, int, long, float and double to 0 and boolean to false. Explicit initialization of volatile variable to a value the same as the default implicit initialized value results in an unnecessary store and membar operation._
>
> As I can see there are a few more zero-initializations of volatiles. Are they intentionally skipped?
> 1. sun.lwawt.macosx.CPlatformEmbeddedFrame#screenX
> 2. sun.lwawt.macosx.CPlatformEmbeddedFrame#screenY
> 3. sun.lwawt.macosx.CWarningWindow#currentIcon
> 4. com.sun.media.sound.SoftSynthesizer.WeakAudioStream#silent_samples
@turbanoff nice catch! I've missed them in my original commit, no intention here. I've included them either.
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PR: https://git.openjdk.java.net/jdk/pull/5197
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