Re: [HACKERS] BUG #4961: pg_standby.exe crashes with no args

Yeah, the patch I think breaks things isn't included in 8.3.7 - it
will be in 8.3.8 though...

//Magnus

On Wed, Aug 12, 2009 at 11:08, wader2<wader2(at)jcom(dot)home(dot)ne(dot)jp> wrote:
> I can't compile nor read source, but can tell you that
> pg_standby.exe in 8.3.7 works fine.
>
> Magnus Hagander wrote:
>>
>> On Mon, Aug 10, 2009 at 20:44, Tom Lane<tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>>
>>> Magnus Hagander <magnus(at)hagander(dot)net> writes:
>>>>
>>>> If I just move those two lines into the #ifndef WIN32 block just
>>>> around it, it compiles and doesn't crash on running-with-no-arguments.
>>>> I haven't tried to actually use it though - can someone confirm if
>>>> this will actually make pg_standby not work properly?
>>>
>>> It would mean there's no way to trigger failover via signal.
>>>
>>> I think what we need is for pg_ctl to be able to send these signals...
>>
>> Those signals don't *exist* on Windows. The whole idea of
>> cross-process signals don't *exist* on Windows.
>>
>> We emulate it in the main backend, by creating a background thread
>> that sets a global variable. That is then polled in the
>> CHECK_FOR_INTERRUPTS macro.  pg_ctl is perfectly capable of sending
>> these signals, but pg_standby can't receive them.
>>
>> We could implement the same type of check in pg_standby, but it
>> requires something like CHECK_FOR_INTERRUPTS. And these interrupts
>> won't, by default, cause any kind of interruption of the process. In
>> the backend, we interrupt socket calls because we have the socket
>> wrapper layer, and nothing else. I don't know how doable this would be
>> in pg_standby - does it always block on a single thing where we could
>> stick some win32 synchronization code? If it's a single, or limited,
>> places we could implement something similar to the backend. But if we
>> need to interrupt at arbitrary locations, that's just not possible.
>>
>>
>
>

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/