Re: Checkpoint not retrying failed fsync? - Mailing list pgsql-hackers

From Andrew Gierth
Subject Re: Checkpoint not retrying failed fsync?
Date
Msg-id 87tvspi652.fsf@news-spur.riddles.org.uk
Whole thread Raw
In response to Re: Checkpoint not retrying failed fsync?  (Thomas Munro <thomas.munro@enterprisedb.com>)
Responses Re: Checkpoint not retrying failed fsync?  (Thomas Munro <thomas.munro@enterprisedb.com>)
List pgsql-hackers
>>>>> "Thomas" == Thomas Munro <thomas.munro@enterprisedb.com> writes:

 >> As far as I can tell from reading the code, if a checkpoint fails the
 >> checkpointer is supposed to keep all the outstanding fsync requests for
 >> next time. Am I wrong, or is there some failure in the logic to do this?

 Thomas> Yikes.  I think this is suspicious:

Yes, tracing through a checkpoint shows that this is clearly wrong.

 Thomas> Why is it OK to unlink the bitmapset? We still need its
 Thomas> contents, in the case that the fsync fails!

Right.

But I don't think just copying the value is sufficient; if a new bit was
set while we were processing the old ones, how would we know which to
clear? We couldn't just clear all the bits afterwards because then we
might lose a request.

-- 
Andrew (irc:RhodiumToad)


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