Re: CommitFest 2009-07: Yay, Kevin! Thanks, reviewers!

Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> On 19/08/10 16:38, Tom Lane wrote:
>> Considering that pg_usleep is implemented with select, I'm not following
>> what you mean by "replace pg_usleep() with select()"?

> Instead of using pg_usleep(), call select() directly, waiting not only
> for the timeout, but also for data to arrive on the "self-pipe". The
> signal handler writes a byte to the self-pipe, waking up the select().
> That way the select() is interupted by the signal arriving, even if
> signals per se don't interrupt it. And it closes the race condition
> involved with setting a flag in the signal handler and checking that in
> the main loop.

Hmm, but couldn't you still do that inside pg_usleep? Signal handlers
that do that couldn't know if they were interrupting a sleep per se,
so this would have to be a backend-wide convention.

regards, tom lane