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Re: do we EXEC_BACKEND on Mac OS X?

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: do we EXEC_BACKEND on Mac OS X?
Date: 2012-10-03 16:15:35
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Lists: pgsql-hackers
On Wed, Oct 3, 2012 at 01:05:54PM -0300, Alvaro Herrera wrote:
> See the CAVEATS here:
> e/ManPages/man2/fork.2.html
> Apparently fork() without exec() isn't all that well supported.
> Noticed while perusing

I think this comment is more relevant:

	Ah, OK, I found this

        It seems that from 10.5 this caveat was added to the official OS
        X documentation. In that light I think it's safest to conclude
        that Apple realised fork() is hard (check out the long list
        of things a current Linux fork does to retain sanity in the
        face of threads, asynchronous I/O, capabilities and other fun
        toys that didn't exist at the dawn of Unix) and decided they
        don't care. It will probably work, but if it doesn't they aren't
        interested in explaining why/ fixing the problem.

        On balance I agree this makes OS X a pretty shoddy Unix, but
        then, I would have been easily persuaded of that anyway.

I am hesitant to avoid fork() on OS/X until someone reports a problem; 
the slowdown would be significant, and I don't think we use enough OS/X
libraries to cause a problem for us, though Bonjour might be a problem.

Anyway, good you asked and we should be aware of possible problems.

  Bruce Momjian  <bruce(at)momjian(dot)us>

  + It's impossible for everything to be true. +

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