From 558571afc7c42c47243836c411ad86fc6c0577c5 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 31 Oct 2018 17:04:43 -0400 Subject: [PATCH] Fix memory leak in repeated SPGIST index scans. spgendscan neglected to pfree all the memory allocated by spgbeginscan. It's possible to get away with that in most normal queries, since the memory is allocated in the executor's per-query context which is about to get deleted anyway; but it causes severe memory leakage during creation or filling of large exclusion-constraint indexes. Also, document that amendscan is supposed to free what ambeginscan allocates. The docs' lack of clarity on that point probably caused this bug to begin with. (There is discussion of changing that API spec going forward, but I don't think it'd be appropriate for the back branches.) Per report from Bruno Wolff. It's been like this since the beginning, so back-patch to all active branches. In HEAD, also fix an independent leak caused by commit 2a6368343 (allocating memory during spgrescan instead of spgbeginscan, which might be all right if it got cleaned up, but it didn't). And do a bit of code beautification on that commit, too. Discussion: https://postgr.es/m/20181024012314.GA27428@wolff.to --- doc/src/sgml/indexam.sgml | 3 ++- src/backend/access/spgist/spgscan.c | 8 ++++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml index 40f201b11b..a613ae7ddc 100644 --- a/doc/src/sgml/indexam.sgml +++ b/doc/src/sgml/indexam.sgml @@ -591,7 +591,8 @@ amendscan (IndexScanDesc scan); End a scan and release resources. The scan struct itself should not be freed, but any locks or pins taken internally by the - access method must be released. + access method must be released, as well as any other memory allocated + by ambeginscan and other scan-related functions. diff --git a/src/backend/access/spgist/spgscan.c b/src/backend/access/spgist/spgscan.c index 1e476681ea..3fe77831d1 100644 --- a/src/backend/access/spgist/spgscan.c +++ b/src/backend/access/spgist/spgscan.c @@ -240,6 +240,14 @@ spgendscan(IndexScanDesc scan) MemoryContextDelete(so->tempCxt); MemoryContextDelete(so->traversalCxt); + + if (so->keyData) + pfree(so->keyData); + + if (so->state.deadTupleStorage) + pfree(so->state.deadTupleStorage); + + pfree(so); } /* -- 2.40.0