From 05172f1f37496acc13769b8cc0af6e77591be90f Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 23 Feb 2023 15:40:27 -0500 Subject: [PATCH] Don't repeatedly register cache callbacks in pgoutput plugin. Multiple cycles of starting up and shutting down the plugin within a single session would eventually lead to "out of relcache_callback_list slots", because pgoutput_startup blindly re-registered its cache callbacks each time. Fix it to register them only once, as all other users of cache callbacks already take care to do. This has been broken all along, so back-patch to all supported branches. Shi Yu Discussion: https://postgr.es/m/OSZPR01MB631004A78D743D68921FFAD3FDA79@OSZPR01MB6310.jpnprd01.prod.outlook.com --- src/backend/replication/pgoutput/pgoutput.c | 26 +++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c index 98377c094b..0df1acbb7a 100644 --- a/src/backend/replication/pgoutput/pgoutput.c +++ b/src/backend/replication/pgoutput/pgoutput.c @@ -409,6 +409,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt, bool is_init) { PGOutputData *data = palloc0(sizeof(PGOutputData)); + static bool publication_callback_registered = false; /* Create our memory context for private allocations. */ data->context = AllocSetContextCreate(ctx->context, @@ -504,9 +505,18 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt, /* Init publication state. */ data->publications = NIL; publications_valid = false; - CacheRegisterSyscacheCallback(PUBLICATIONOID, - publication_invalidation_cb, - (Datum) 0); + + /* + * Register callback for pg_publication if we didn't already do that + * during some previous call in this process. + */ + if (!publication_callback_registered) + { + CacheRegisterSyscacheCallback(PUBLICATIONOID, + publication_invalidation_cb, + (Datum) 0); + publication_callback_registered = true; + } /* Initialize relation schema cache. */ init_rel_sync_cache(CacheMemoryContext); @@ -1745,7 +1755,7 @@ pgoutput_origin_filter(LogicalDecodingContext *ctx, * Shutdown the output plugin. * * Note, we don't need to clean the data->context and data->cachectx as - * they are child context of the ctx->context so it will be cleaned up by + * they are child contexts of the ctx->context so they will be cleaned up by * logical decoding machinery. */ static void @@ -1931,7 +1941,9 @@ static void init_rel_sync_cache(MemoryContext cachectx) { HASHCTL ctl; + static bool relation_callbacks_registered = false; + /* Nothing to do if hash table already exists */ if (RelationSyncCache != NULL) return; @@ -1946,6 +1958,10 @@ init_rel_sync_cache(MemoryContext cachectx) Assert(RelationSyncCache != NULL); + /* No more to do if we already registered callbacks */ + if (relation_callbacks_registered) + return; + /* We must update the cache entry for a relation after a relcache flush */ CacheRegisterRelcacheCallback(rel_sync_cache_relation_cb, (Datum) 0); @@ -1968,6 +1984,8 @@ init_rel_sync_cache(MemoryContext cachectx) CacheRegisterSyscacheCallback(PUBLICATIONNAMESPACEMAP, rel_sync_cache_publication_cb, (Datum) 0); + + relation_callbacks_registered = true; } /*