Re: Multiplexing SUGUSR1

Tom Lane wrote:
> Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
>> To set or clear the flag from PGPROC, to send or handle a signal, we
>> have to acquire ProcArrayLock. Is that safe to do in a signal handler?
>
> No. If it's trying to do that then it's broken. In fact, if it's
> trying to do much of anything beyond setting a "volatile" flag variable
> in a signal handler, it's broken --- unless there are special provisions
> to limit where the signal trap can occur, which would be pretty much
> unacceptable for a multiplexed-signal implementation.

Ok, I was afraid so.

I think we'll need to replace the proposed bitmask with an array of
sig_atomic_t flags then, and do without locking.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com