Re: [HACKERS] Fix mdsync never-ending loop problem

From: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>, pgsql-patches(at)postgresql(dot)org, Simon Riggs <simon(at)2ndquadrant(dot)com>
Subject: Re: [HACKERS] Fix mdsync never-ending loop problem
Date: 2007-04-11 07:19:24
Message-ID: 461C8BFC.6000204@enterprisedb.com
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Tom Lane wrote:
> I wrote:
>> Actually, on second look I think the key idea here is Takahiro-san's
>> introduction of a cancellation flag in the hashtable entries, to
>> replace the cases where AbsorbFsyncRequests can try to delete entries.
>> What that means is mdsync() doesn't need an outer retry loop at all:
>
> I fooled around with this idea and came up with the attached patch.
> It seems to do what's intended but could do with more eyeballs and
> testing before committing. Comments please?

I'm traveling today, but I'll take a closer look at it tomorrow morning.
My first thought is that the cycle_ctr just adds extra complexity. The
canceled-flag really is the key in Takahiro-san's patch, so we don't
need the cycle_ctr anymore.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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