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Re: [HACKERS] socket calls in signal handler (WAS:

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Claudio Natoli <claudio(dot)natoli(at)memetrics(dot)com>
Cc: pgsql-hackers-win32(at)postgresql(dot)org
Subject: Re: [HACKERS] socket calls in signal handler (WAS:
Date: 2004-03-17 13:20:39
Message-ID: 200403171320.i2HDKdX22253@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers-win32
Magnus is still researching the APC issue.  I am talking to him
regularly on this item.

---------------------------------------------------------------------------

Claudio Natoli wrote:
> 
> [reviving this at great personal risk on win32]
> 
> > Claudio Natoli wrote:
> > > The specific (and possibly only? are their others?) issue is the call to
> > > pgstat_beterm from reaper/CleanupProc, invoked by a SIGCHLD. Can this
> call
> > > be deferred to the main loop (ie. ServerLoop) and is there any merit in
> > > doing so? 
> > 
> > Just canvassing for options. If we can get a win32 specific 
> > change that we trust, great! (I think it goes without saying 
> > that, throughout the work on this port, we've tried to avoid 
> > changing the existing code as much as possible). However, if 
> > we can not, I'd like to have other options, and am exploring 
> > this possibility.
> 
> How are we going to work around this issue?
> 
> ISTM we have four options:
> (a) Finding out for sure whether or not socket calls within APCs mash the
> state of the internal socket libs etc.  We (now) know that a socket call
> within an APC will cause a currently blocked socket call to fail without
> error, but is anything else hammered that we don't (yet) know about? If we
> can determine that the answer is no, we have a simple work-around (ie.
> setting a flag like APCcalled, and checking on return from select...)
> (b) Another win32 work-around (like pushing the pgstat_send call out on a
> separate thread, if allowed)
> (c) Deferring the pgstat_beterm call
> and, ah:
> (d) Rewriting the win32 signal code
> 
> Ok. So we really have (at most) three options :-)
> 
> Is (c) out of the question?  And, regardless of the answer to this, does
> anyone have a definitive answer to (a), or what might be allowed in (b)?
> 
> Cheers,
> Claudio
> 
> 
> 
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-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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