postgres.git / summary / log / commit / refs

commit    e749eaf46e9b05d25592d9c83bde7fb026e9c6eb
Author:   Michael Paquier <michael@paquier.xyz>
Date:     Thu Nov 21 06:14:13 2024 +0000

    Fix memory leak in pgoutput for the WAL sender
    
    RelationSyncCache, the hash table in charge of tracking the relation
    schemas sent through pgoutput, was forgetting to free the TupleDesc
    associated to the two slots used to store the new and old tuples,
    causing some memory to be leaked each time a relation is invalidated
    when the slots of an existing relation entry are cleaned up.
    
    This is rather hard to notice as the bloat is pretty minimal, but a
    long-running WAL sender would be in trouble over time depending on the
    workload.  sysbench has proved to be pretty good at showing the problem,
    coupled with some memory monitoring of the WAL sender.
    
    Issue introduced in 52e4f0cd472d, that has added row filters for tables
    logically replicated.
    
    Author: Boyu Yang
    Reviewed-by: Michael Paquier, Hou Zhijie
    Discussion: https://postgr.es/m/DM3PR84MB3442E14B340E553313B5C816E3252@DM3PR84MB3442.NAMPRD84.PROD.OUTLOOK.COM
    Backpatch-through: 15


 src/backend/replication/pgoutput/pgoutput.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index c57c5ed8de9..bb8f3ea702f 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -2046,10 +2046,34 @@ get_rel_sync_entry(PGOutputData *data, Relation relation)
 		 * Tuple slots cleanups. (Will be rebuilt later if needed).
 		 */
 		if (entry->old_slot)
+		{
+			TupleDesc	desc = entry->old_slot->tts_tupleDescriptor;
+
+			Assert(desc->tdrefcount == -1);
+
 			ExecDropSingleTupleTableSlot(entry->old_slot);
+
+			/*
+			 * ExecDropSingleTupleTableSlot() would not free the TupleDesc, so
+			 * do it now to avoid any leaks.
+			 */
+			FreeTupleDesc(desc);
+		}
 		if (entry->new_slot)
+		{
+			TupleDesc	desc = entry->new_slot->tts_tupleDescriptor;
+
+			Assert(desc->tdrefcount == -1);
+
 			ExecDropSingleTupleTableSlot(entry->new_slot);
 
+			/*
+			 * ExecDropSingleTupleTableSlot() would not free the TupleDesc, so
+			 * do it now to avoid any leaks.
+			 */
+			FreeTupleDesc(desc);
+		}
+
 		entry->old_slot = NULL;
 		entry->new_slot = NULL;
 


[parent: fe084039e482]