Re: Using WaitEventSet in the postmaster

On Sat, Dec 3, 2022 at 10:41 AM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> Here's an iteration like that. Still WIP grade. It passes, but there
> must be something I don't understand about this computer program yet,
> because if I move the "if (pending_..." section up into the block
> where WL_LATCH_SET has arrived (instead of testing those variables
> every time through the loop), a couple of tests leave zombie
> (unreaped) processes behind, indicating that something funky happened
> to the state machine that I haven't yet grokked. Will look more next
> week.

Duh. The reason for that was the pre-existing special case for
PM_WAIT_DEAD_END, which used a sleep(100ms) loop to wait for children
to exit, which I needed to change to a latch wait. Fixed in the next
iteration, attached.

The reason for the existing sleep-based approach was that we didn't
want to accept any more connections (or spin furiously because the
listen queue was non-empty). So in this version I invented a way to
suppress socket events temporarily with WL_SOCKET_IGNORE, and then
reactivate them after crash reinit.

Still WIP, but I hope travelling in the right direction.