Re: Multiplexing SUGUSR1

Hi,

On Mon, Dec 8, 2008 at 11:39 PM, Heikki Linnakangas
<heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
> 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.

Thanks! I updated the patch so (based on signal_handling_v2-heikki-1.patch).

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center