RFR: 8319447: Improve performance of delayed task handling [v6]

[Alan Bateman]

On Wed, 5 Mar 2025 23:55:52 GMT, Sunmisc Unsafe <duke at openjdk.org> wrote:

>> src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 3741:
>> 
>>> 3739:     public <V> ForkJoinTask<V> submitWithTimeout(Callable<V> callable,
>>> 3740:                                                  long timeout, TimeUnit unit,
>>> 3741:                                                  Consumer<ForkJoinTask<V>> timeoutAction) {
>> 
>> I wonder if the variance of the Consumer to this method should be more permissible. Something like:
>> 
>> public <V> ForkJoinTask<V> submitWithTimeout(Callable<V> callable,
>>                                                  long timeout, TimeUnit unit,
>>                                                  Consumer<? super ForkJoinTask<? extends V>> timeoutAction) {
>
> Maybe it's worth using java.time.Duration, although it doesn't fit into the API very elegantly.

> I wonder if the variance of the Consumer to this method should be more permissible. Something like:
> 
> public ForkJoinTask submitWithTimeout(Callable callable, long timeout, TimeUnit unit, Consumer<? super ForkJoinTask<? extends V>> timeoutAction) {

I think this is a good point but it might be more practical to limit it to just a contravariant Consumer, as in ` Consumer<? super ForkJoinTask<V>>`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23702#discussion_r1983469247