Re: Fix overflow of bgwriter's request queue

"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote
>
> Yes, the patch is wrong as-is because it may lose uncompleted fsyncs.
> But I think that we could just add the AbsorbFsyncRequests call in the
> fsync loop and not worry about trying to avoid doing extra fsyncs.
>
> Another possibility is to make the copied list as in the patch, but
> HASH_REMOVE an entry only after doing the fsync successfully --- as long
> as you don't AbsorbFsyncRequests between doing the fsync and removing
> the entry, you aren't risking missing a necessary fsync. I'm
> unconvinced that this is worth the trouble, however.
>

Maybe the take a copied list is safer. I got a little afraid of doing
seqscan hash while doing HASH_ENTER at the same time. Do we have this kind
of hash usage somewhere?

Regards,
Qingqing