From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Robert Haas <robertmhaas(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: | 2017-06-07 10:05:50 |
Message-ID: | CAA4eK1J_wYRDrOM+m3hah9OmwGRCYz1KA4fxRA9zbWqXuhdyzQ@mail.gmail.com |
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Lists: | pgsql-hackers |
On Tue, Jun 6, 2017 at 10:14 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> 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.
>
I think it won't create an additional risk, because the idea is that
if we fail to map the shm segment at a predefined address, then we
will allow the system to choose the initial address as we are doing
now. So, it can reduce chances of doing retries.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
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