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Fix statistics breakage from bgwriter/checkpointer process split.

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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.)
This commit is contained in:
Tom Lane 2012-07-18 15:40:31 -04:00
parent 4a9c30a8a1
commit 80e373c3a8
1 changed files with 4 additions and 2 deletions
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6
src/backend/postmaster/checkpointer.c
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@ -1132,7 +1132,8 @@ ForwardFsyncRequest(RelFileNode rnode, ForkNumber forknum, BlockNumber segno)
LWLockAcquire(CheckpointerCommLock, LW_EXCLUSIVE); LWLockAcquire(CheckpointerCommLock, LW_EXCLUSIVE);
/* Count all backend writes regardless of if they fit in the queue */ /* 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 * If the checkpointer isn't running or the request queue is full, the
@ -1147,7 +1148,8 @@ ForwardFsyncRequest(RelFileNode rnode, ForkNumber forknum, BlockNumber segno)
* Count the subset of writes where backends have to do their own * Count the subset of writes where backends have to do their own
* fsync * fsync
*/ */
CheckpointerShmem->num_backend_fsync++; if (!AmBackgroundWriterProcess())
CheckpointerShmem->num_backend_fsync++;
LWLockRelease(CheckpointerCommLock); LWLockRelease(CheckpointerCommLock);
return false; return false;
} }