postgres.git / summary / log / commit / refs

commit    1e9326d6a3efcb5648a85c1653cc263bc787efa0
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Wed Jul 18 19:40:35 2012 +0000
First released in: 9.3.0, 9.2.0

    Fix statistics breakage from bgwriter/checkpointer process split.
    
    ForwardFsyncRequest() supposed that it could only be called in regular
    backends, which used to be true; but since the splitup of bgwriter and
    checkpointer, it is also called in the bgwriter.  We do not want to count
    such calls in pg_stat_bgwriter.buffers_backend statistics, so fix things
    so that they aren't.
    
    (It's worth noting here that this implies an alarmingly large increase in
    the expected amount of cross-process fsync request traffic, which may well
    mean that the process splitup was not such a hot idea.)


 src/backend/postmaster/checkpointer.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index aa5577d3570..ec5690bb69c 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -1135,7 +1135,8 @@ ForwardFsyncRequest(RelFileNode rnode, ForkNumber forknum, BlockNumber segno)
 	LWLockAcquire(CheckpointerCommLock, LW_EXCLUSIVE);
 
 	/* Count all backend writes regardless of if they fit in the queue */
-	CheckpointerShmem->num_backend_writes++;
+	if (!AmBackgroundWriterProcess())
+		CheckpointerShmem->num_backend_writes++;
 
 	/*
 	 * If the checkpointer isn't running or the request queue is full, the
@@ -1150,7 +1151,8 @@ ForwardFsyncRequest(RelFileNode rnode, ForkNumber forknum, BlockNumber segno)
 		 * Count the subset of writes where backends have to do their own
 		 * fsync
 		 */
-		CheckpointerShmem->num_backend_fsync++;
+		if (!AmBackgroundWriterProcess())
+			CheckpointerShmem->num_backend_fsync++;
 		LWLockRelease(CheckpointerCommLock);
 		return false;
 	}


[parent: d843589e5ab3]