RFR: 8313697: [XWayland][Screencast] consequent getPixelColor calls are slow [v3]

[Phil Race]

On Mon, 14 Aug 2023 14:12:59 GMT, Alexander Zvegintsev <azvegint at openjdk.org> wrote:

>> Right now, each call to getPixelColor/createScreenCapture opens and closes a ScreenCast session. 
>> When there are many such calls in a row, it becomes a rather time-consuming operation.
>> 
>> For example,
>> 
>> 
>> for (int i = 0; i < 50; i++) {
>>     for (int j = 0; j < 50; j++) {
>>         robot.getPixelColor(i, j);
>>     }
>> } 
>> 
>> `50x50 took 375219ms`
>> 
>> This fix offers optimization by keeping the session open and closing it only 2 seconds after the last activity.
>> 
>> `50x50 took 28113ms` which is ~ 13 times faster.
>> 
>> Testing looks good.
>
> Alexander Zvegintsev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix app exit issue

Marked as reviewed by prr (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/15250#pullrequestreview-1583557408