Re: Checkpoint gets stuck in mdsync

Heikki Linnakangas <heikki(at)enterprisedb(dot)com> wrote:

> Now that the CheckpointStartLock starvation has been taken care of, I'm
> seeing another problem with checkpoints in my test run: mdsync never
> finishes.
>
> My proposed fix is to make a copy of pendingOpsTable before entering the
> loop. AbsorbFsyncRequest will put new requests to a fresh new
> pendingOpsTable, while the mdsync loop will drain the copy. I'll write a
> patch along those lines if there's no better ideas.

Yeah, I'm also anxious about the stuck. I wrote a fix to use a copy of
pendingOpsTable as you said, when I implemented Load distributed checkpoint
patch. (http://momjian.us/mhonarc/patches/msg00025.html) It would make me
very happy if you review my patch and check whether my fix is proper.

There was another reason to fix it in my patch. I wanted to fsync files
only once for each file because bgwriter sleeps for each file in my patch.

Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center