RFR: 8286597: Implement PollerProvider on AIX [v9]

[Alan Bateman]

On Fri, 19 May 2023 15:45:45 GMT, Vyom Tewari <vtewari at openjdk.org> wrote:

>> You must be very positive about the AIX implementation of malloc/free. :-)
>> malloc/free may:
>> - be slower than desired
>> - cause fragmentation
>> - not return some of the freed memory to the OS
>> 
>> I don't know how well it is on AIX. So, I agree with Alan. That should better get checked.
>
> there will be some performance impact  in "allocation/de-allocation"  memory  per poll approach.

> The other implementations allocate a fixed size array at object creation. This imposes an upper limit on the number of fds that can be polled. I made the decision to move this allocation to the poll call and track the size of the poll set. This way, (1) the only limit to the size of the poll set is the system limit on number of open fds (if you can open an fd it can be polled) (2) there is no wasted space to an arbitrarily large array when there are only a few fds polled.

I don't have any experience on AIX but docs page for pollset_poll suggests it populates the array with the file descriptors that have pending events. If I read this correctly, then it's nothing to do with the number of file descriptors registered and it works similarly to /dev/poll, epoll and kqueue. So I think maybe look at this again.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13452#discussion_r1199199710