RFR: Support yield on virtual thread on EPollSelector select() [v2]

[joeyleeeeeee97]

On Thu, 28 Apr 2022 05:16:48 GMT, Alan Bateman <alanb at openjdk.org> wrote:

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>>   Support yield on virtual thread on EPollSelector select()
>
> Selection operations are specified to synchronize on the Selector so we can't change the locking without incompatible changes to the specification. So yes, selection operation on a virtual threads pin the carrier. It is something that can be re-examined once restriction on Java monitors is addressed.

@AlanBateman , Thanks for the tip.  
Does loom consider providing the ability to customize the 'Poller' threads?  For example Netty is using [native implementation](https://netty.io/wiki/native-transports.html) .
If loom provides the ability for users to decide where to register blocking operation and how to cooperate with scheduler, frameworks developers could build up their `IO Poller`. 
For example if loom could opens ability to register blocking event to Poller, and let user start their customized poller as IO mutiplexer.

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PR: https://git.openjdk.java.net/loom/pull/166