On Wed, 27 May 2026 02:44:59 GMT, Phil Race <[email protected]> wrote:
>> AFAICS, we can get into a situation where a posted event is silently ignored
>> if the event EQ has not been initialized by that point.
>> Previously, we always had AppContext initialized when `postEvent()` was
>> called, correct me if I am wrong.
>>
>>
>>> In postEvent() itself was the only other option that worked but then it is
>>> checked every time an event is posted.
>>
>> We can make the check relatively cheap in `postEvent()`, for example:
>>
>>
>> PostEventQueue eq = postEventQueue; // volatile read
>> if (eq == null) {
>> initEQ(); // call synchronized method only when necessary
>> eq = postEventQueue;
>> }
>> eq.postEvent(event);
>>
>>
>> ---
>>
>> Regardless of whether we implement this change in `postEvent()`, we can
>> apply the same optimization in `getSystemEventQueueImplPP()` to avoid
>> calling a synchronized method every time:
>>
>>
>> public static EventQueue getSystemEventQueueImplPP() {
>> EventQueue eq = currentEventQueue;
>> if (eq == null) {
>> initEQ();
>> eq = currentEventQueue;
>> }
>> return eq;
>> }
>
>> AFAICS, we can get into a situation where a posted event is silently ignored
>> if the event EQ has not been initialized by that point.
>
> So we need to make sure it is. And there are two ways to do it. I've opted
> for one of them.
>
>> Previously, we always had AppContext initialized when `postEvent()` was
>> called, correct me if I am wrong.
>
> Not by design as far as I can tell. If it was true it was by accident.
>
>
>>
>> > In postEvent() itself was the only other option that worked but then it is
>> > checked every time an event is posted.
>>
>> We can make the check relatively cheap in `postEvent()`, for example:
>>
>> ```java
>> PostEventQueue eq = postEventQueue; // volatile read
>> if (eq == null) {
>> initEQ(); // call synchronized method only when necessary
>> eq = postEventQueue;
>> }
>> eq.postEvent(event);
>
> Yes, I know and that is the pattern I would use if we went that route.
>
>> ```
>>
>> Regardless of whether we implement this change in `postEvent()`, we can
>> apply the same optimization in `getSystemEventQueueImplPP()` to avoid
>> calling a synchronized method every time:
>
> That's true, and I thought about it but it didn't seem a big deal because
> that's infrequent and no different than today
>>
>> ```java
>> public static EventQueue getSystemEventQueueImplPP() {
>> EventQueue eq = currentEventQueue;
>> if (eq == null) {
>> initEQ();
>> eq = currentEventQueue;
>> }
>> return eq;
>> }
>> ```
If we want to always init in the constructor, then we can drop initialization
in `getSystemEventQueueImplPP` and make it unconditional?
It is also unclear how it is interact with `EventQueue.push` which may change
`SunToolkit.currentEventQueue` but not `SunToolkit.postEventQueue`, I cannot
find a way to init it out of order, but maybe it is possible?
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/31262#discussion_r3312607269
