diff options
| -rw-r--r-- | src/backend/postmaster/bgwriter.c | 8 | ||||
| -rw-r--r-- | src/backend/storage/smgr/md.c | 11 |
2 files changed, 11 insertions, 8 deletions
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c index a4d758d536a..d8c7c3aa13b 100644 --- a/src/backend/postmaster/bgwriter.c +++ b/src/backend/postmaster/bgwriter.c @@ -37,7 +37,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.40 2007/06/30 19:12:01 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.41 2007/07/03 14:51:24 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1007,9 +1007,9 @@ ForwardFsyncRequest(RelFileNode rnode, BlockNumber segno) * Retrieve queued fsync requests and pass them to local smgr. * * This is exported because it must be called during CreateCheckPoint; - * we have to be sure we have accepted all pending requests *after* we - * establish the checkpoint REDO pointer. Since CreateCheckPoint - * sometimes runs in non-bgwriter processes, do nothing if not bgwriter. + * we have to be sure we have accepted all pending requests just before + * we start fsync'ing. Since CreateCheckPoint sometimes runs in + * non-bgwriter processes, do nothing if not bgwriter. */ void AbsorbFsyncRequests(void) diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c index 3ac3e8f4e73..251811421e0 100644 --- a/src/backend/storage/smgr/md.c +++ b/src/backend/storage/smgr/md.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/smgr/md.c,v 1.128 2007/04/12 17:10:55 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/storage/smgr/md.c,v 1.129 2007/07/03 14:51:24 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -880,9 +880,12 @@ mdsync(void) /* * If we are in the bgwriter, the sync had better include all fsync - * requests that were queued by backends before the checkpoint REDO - * point was determined. We go that a little better by accepting all - * requests queued up to the point where we start fsync'ing. + * requests that were queued by backends up to this point. The tightest + * race condition that could occur is that a buffer that must be written + * and fsync'd for the checkpoint could have been dumped by a backend + * just before it was visited by BufferSync(). We know the backend will + * have queued an fsync request before clearing the buffer's dirtybit, + * so we are safe as long as we do an Absorb after completing BufferSync(). */ AbsorbFsyncRequests(); |