Re: [Patch] Optimize dropping of relation buffers using dlist

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Thomas Munro <thomas(dot)munro(at)gmail(dot)com>
Cc: "k(dot)jamison(at)fujitsu(dot)com" <k(dot)jamison(at)fujitsu(dot)com>, "tsunakawa(dot)takay(at)fujitsu(dot)com" <tsunakawa(dot)takay(at)fujitsu(dot)com>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, "amit(dot)kapila16(at)gmail(dot)com" <amit(dot)kapila16(at)gmail(dot)com>, "andres(at)anarazel(dot)de" <andres(at)anarazel(dot)de>, "robertmhaas(at)gmail(dot)com" <robertmhaas(at)gmail(dot)com>, "tomas(dot)vondra(at)2ndquadrant(dot)com" <tomas(dot)vondra(at)2ndquadrant(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [Patch] Optimize dropping of relation buffers using dlist
Date: 2020-10-22 04:52:00
Message-ID: 252311.1603342320@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Thomas Munro <thomas(dot)munro(at)gmail(dot)com> writes:
> Hmmm. The Linux comment led me to commit ffae5cc and a 2006 thread[1]
> showing a buggy sequence of system calls.

Hah, blast from the past ...

> AFAICS it was not even an
> SMP/race problem of the type you might half expect, it was a single
> process not seeing its own write. I didn't find details on the
> version, filesystem etc.

Per the referenced bug-reporting thread, it was ReiserFS and/or NFS on
SLES 9.3; so, dubious storage choices on an ancient-even-then Linux
kernel.

I think the takeaway point is not so much that that particular bug
might recur as that storage infrastructure does sometimes have bugs.
If you're wanting to introduce new assumptions about what the filesystem
will do, it's prudent to think about how badly will we break if the
assumptions fail.

regards, tom lane

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Kyotaro Horiguchi 2020-10-22 04:54:16 Re: Add statistics to pg_stat_wal view for wal related parameter tuning
Previous Message Joel Mariadasan (jomariad) 2020-10-22 04:46:04 User accounts on windows