Re: retry shm attach for windows (WAS: Re: OK, so culicidae is *still* broken)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: retry shm attach for windows (WAS: Re: OK, so culicidae is *still* broken)
Date: 2017-06-06 16:44:02
Message-ID: 20891.1496767442@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> I think the idea of retrying process creation (and I definitely agree
> with Tom and Magnus that we have to retry process creation, not just
> individual mappings) is a good place to start. Now if we find that we
> are having to retry frequently, then I think we might need to try
> something along the lines of what Andres proposed and what nginx
> apparently did. However, any fixed address will be prone to
> occasional failures (or maybe, on some systems, regular failures) if
> that particular address happens to get claimed by something. I don't
> think we can say that there is any address where that definitely won't
> happen. So I would say let's do this retry thing first, and then if
> that proves inadequate, we can also try moving the mappings to a range
> where conflicts are less likely.

By definition, the address range we're trying to reuse worked successfully
in the postmaster process. I don't see how forcing a specific address
could do anything but create an additional risk of postmaster startup
failure.

regards, tom lane

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