From 5df319f3d55d09fadb4f7e4b58c5b476a3aeceb4 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Mon, 20 Mar 2023 21:57:40 -0700 Subject: [PATCH] Fix memory leak and inefficiency in CREATE DATABASE ... STRATEGY WAL_LOG RelationCopyStorageUsingBuffer() did not free the strategies used to access the source / target relation. They memory was released at the end of the transaction, but when using a template database with a lot of relations, the temporary leak can become big prohibitively big. RelationCopyStorageUsingBuffer() acquired the buffer for the target relation with RBM_NORMAL, therefore requiring a read of a block guaranteed to be zero. Use RBM_ZERO_AND_LOCK instead. Reviewed-by: Robert Haas Discussion: https://postgr.es/m/20230321070113.o2vqqxogjykwgfrr@awork3.anarazel.de Backpatch: 15-, where STRATEGY WAL_LOG was introduced --- src/backend/storage/buffer/bufmgr.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 0a05577b68..95212a3941 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -3833,11 +3833,9 @@ RelationCopyStorageUsingBuffer(RelFileLocator srclocator, LockBuffer(srcBuf, BUFFER_LOCK_SHARE); srcPage = BufferGetPage(srcBuf); - /* Use P_NEW to extend the destination relation. */ dstBuf = ReadBufferWithoutRelcache(dstlocator, forkNum, blkno, - RBM_NORMAL, bstrategy_dst, + RBM_ZERO_AND_LOCK, bstrategy_dst, permanent); - LockBuffer(dstBuf, BUFFER_LOCK_EXCLUSIVE); dstPage = BufferGetPage(dstBuf); START_CRIT_SECTION(); @@ -3855,6 +3853,9 @@ RelationCopyStorageUsingBuffer(RelFileLocator srclocator, UnlockReleaseBuffer(dstBuf); UnlockReleaseBuffer(srcBuf); } + + FreeAccessStrategy(bstrategy_src); + FreeAccessStrategy(bstrategy_dst); } /* ---------------------------------------------------------------------