On 2018-05-22 20:54:46 +0200, Dmitry Dolgov wrote: > > On 22 May 2018 at 18:47, Andres Freund <and...@anarazel.de> wrote: > > On 2018-05-22 08:57:18 -0700, Andres Freund wrote: > >> Hi, > >> > >> > >> On 2018-05-22 17:37:28 +0200, Dmitry Dolgov wrote: > >> > Thanks for the patch. Out of curiosity I tried to play with it a bit. > >> > >> Thanks. > >> > >> > >> > `pgbench -i -s 100` actually hang on my machine, because the > >> > copy process ended up with waiting after `pg_uds_send_with_fd` > >> > had > >> > >> Hm, that had worked at some point... > >> > >> > >> > errno == EWOULDBLOCK || errno == EAGAIN > >> > > >> > as well as the checkpointer process. > >> > >> What do you mean with that latest sentence? > > To investigate what's happening I attached with gdb to two processes, COPY > process from pgbench and checkpointer (since I assumed it may be involved). > Both were waiting in WaitLatchOrSocket right after SendFsyncRequest.
Huh? Checkpointer was in SendFsyncRequest()? Coudl you share the backtrace? > >> > Looks like with the default > >> > configuration and `max_wal_size=1GB` it writes more than reads to a > >> > socket, and a buffer eventually becomes full. > >> > >> That's intended to then wake up the checkpointer immediately, so it can > >> absorb the requests. So something isn't right yet. > > > > Doesn't hang here, but it's way too slow. > > Yep, in my case it was also getting slower, but eventually hang. > > > Reason for that is that I've wrongly resolved a merge conflict. Attached is > > a > > fixup patch - does that address the issue for you? > > Hm...is it a correct patch? I see the same committed in > 8c3debbbf61892dabd8b6f3f8d55e600a7901f2b, so I can't really apply it. Yea, sorry for that. Too many files in my patch directory... Right one attached. Greetings, Andres Freund
>From 483b98fd21b40e2997a1f164155cae698204ec25 Mon Sep 17 00:00:00 2001 From: Andres Freund <and...@anarazel.de> Date: Tue, 22 May 2018 09:38:58 -0700 Subject: [PATCH] fixup! WIP: Optimize register_dirty_segment() to not repeatedly queue fsync requests. Merge failure. --- src/backend/storage/smgr/md.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c index ae3a5bf023f..942e2dcf788 100644 --- a/src/backend/storage/smgr/md.c +++ b/src/backend/storage/smgr/md.c @@ -1540,6 +1540,8 @@ register_dirty_segment(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg) } else ForwardFsyncRequest(reln->smgr_rnode.node, forknum, seg->mdfd_segno, seg->mdfd_vfd); + + seg->mdfd_dirtied_cycle = cycle; } /* -- 2.17.0.rc1.dirty
