1 files changed, 15 insertions, 18 deletions

diff --git a/contrib/pg_prewarm/autoprewarm.c b/contrib/pg_prewarm/autoprewarm.c
index c01b9c7e6a4..8b68dafc261 100644
--- a/contrib/pg_prewarm/autoprewarm.c
+++ b/contrib/pg_prewarm/autoprewarm.c
@@ -370,6 +370,15 @@ apw_load_buffers(void)
 	apw_state->prewarm_start_idx = apw_state->prewarm_stop_idx = 0;
 	apw_state->prewarmed_blocks = 0;
 
+	/* Don't prewarm more than we can fit. */
+	if (num_elements > NBuffers)
+	{
+		num_elements = NBuffers;
+		ereport(LOG,
+				(errmsg("autoprewarm capping prewarmed blocks to %d (shared_buffers size)",
+						NBuffers)));
+	}
+
 	/* Get the info position of the first block of the next database. */
 	while (apw_state->prewarm_start_idx < num_elements)
 	{
@@ -410,10 +419,6 @@ apw_load_buffers(void)
 		apw_state->database = current_db;
 		Assert(apw_state->prewarm_start_idx < apw_state->prewarm_stop_idx);
 
-		/* If we've run out of free buffers, don't launch another worker. */
-		if (!have_free_buffer())
-			break;
-
 		/*
 		 * Likewise, don't launch if we've already been told to shut down.
 		 * (The launch would fail anyway, but we might as well skip it.)
@@ -462,12 +467,6 @@ apw_read_stream_next_block(ReadStream *stream,
 	{
 		BlockInfoRecord blk = p->block_info[p->pos];
 
-		if (!have_free_buffer())
-		{
-			p->pos = apw_state->prewarm_stop_idx;
-			return InvalidBlockNumber;
-		}
-
 		if (blk.tablespace != p->tablespace)
 			return InvalidBlockNumber;
 
@@ -523,10 +522,10 @@ autoprewarm_database_main(Datum main_arg)
 	blk = block_info[i];
 
 	/*
-	 * Loop until we run out of blocks to prewarm or until we run out of free
+	 * Loop until we run out of blocks to prewarm or until we run out of
 	 * buffers.
 	 */
-	while (i < apw_state->prewarm_stop_idx && have_free_buffer())
+	while (i < apw_state->prewarm_stop_idx)
 	{
 		Oid			tablespace = blk.tablespace;
 		RelFileNumber filenumber = blk.filenumber;
@@ -568,14 +567,13 @@ autoprewarm_database_main(Datum main_arg)
 
 		/*
 		 * We have a relation; now let's loop until we find a valid fork of
-		 * the relation or we run out of free buffers. Once we've read from
-		 * all valid forks or run out of options, we'll close the relation and
+		 * the relation or we run out of buffers. Once we've read from all
+		 * valid forks or run out of options, we'll close the relation and
 		 * move on.
 		 */
 		while (i < apw_state->prewarm_stop_idx &&
 			   blk.tablespace == tablespace &&
-			   blk.filenumber == filenumber &&
-			   have_free_buffer())
+			   blk.filenumber == filenumber)
 		{
 			ForkNumber	forknum = blk.forknum;
 			BlockNumber nblocks;
@@ -864,7 +862,7 @@ apw_init_state(void *ptr)
 {
 	AutoPrewarmSharedState *state = (AutoPrewarmSharedState *) ptr;
 
-	LWLockInitialize(&state->lock, LWLockNewTrancheId());
+	LWLockInitialize(&state->lock, LWLockNewTrancheId("autoprewarm"));
 	state->bgworker_pid = InvalidPid;
 	state->pid_using_dumpfile = InvalidPid;
 }
@@ -883,7 +881,6 @@ apw_init_shmem(void)
 								   sizeof(AutoPrewarmSharedState),
 								   apw_init_state,
 								   &found);
-	LWLockRegisterTranche(apw_state->lock.tranche, "autoprewarm");
 
 	return found;
 }