Re: postmaster.pid

Andrew Dunstan <andrew@dunslane.net> writes:
> Tom Lane wrote:
>> Should you not send the zero signal the same way
>> as other signals, and just let the recipient ignore it?

> Umm - my Linux manpage says that no signal is actually sent in these
> circumstances, just a check that we could send some other signal if we
> wanted to.

Sure, but all that we have to emulate is that there is no visible effect
on the target process.  If it receives and throws away a zero signal,
we're good.  (Especially since this isn't done often enough to be a
performance issue.)

> So Dave's patch is clearly wrong where it returns EINVAL. How we should
> distinguish between the other two cases I am less sure of - IANAWP ;-)

I think we could just return ESRCH always if we have no pipe for the
process.  The callers will actually treat these errnos the same anyway.

            regards, tom lane