v1-0001-Hold-XidGenLock-to-read-TransamVariables-nextXid.patch

application/octet-stream

Filename: v1-0001-Hold-XidGenLock-to-read-TransamVariables-nextXid.patch
Type: application/octet-stream
Part: 0
Message: Re: BUG #18658: Assert in SerialAdd() due to race condition

Patch

Same data as JSON: GET /api/v1/attachments/:id/patch the parsed metadata as JSON — format, series position, per-file stats; never the diff bytes. API reference →
Format: format-patch
Series: patch v1-0001
Subject: Hold XidGenLock to read TransamVariables->nextXid
File+
src/backend/storage/lmgr/predicate.c 2 3
From 8926b83835fb9f0d90318e83150ca6645735140d Mon Sep 17 00:00:00 2001
From: Maxim Orlov <orlovmg@gmail.com>
Date: Wed, 23 Oct 2024 15:44:28 +0300
Subject: [PATCH v1] Hold XidGenLock to read TransamVariables->nextXid

---
 src/backend/storage/lmgr/predicate.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index 2030322f95..6dce4d8443 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -3419,9 +3419,6 @@ ReleasePredicateLocks(bool isCommit, bool isReadOnlySafe)
 	topLevelIsDeclaredReadOnly = SxactIsReadOnly(MySerializableXact);
 
 	/*
-	 * We don't hold XidGenLock lock here, assuming that TransactionId is
-	 * atomic!
-	 *
 	 * If this value is changing, we don't care that much whether we get the
 	 * old or new value -- it is just used to determine how far
 	 * SxactGlobalXmin must advance before this transaction can be fully
@@ -3429,7 +3426,9 @@ ReleasePredicateLocks(bool isCommit, bool isReadOnlySafe)
 	 * transaction to complete before freeing some RAM; correctness of visible
 	 * behavior is not affected.
 	 */
+	LWLockAcquire(XidGenLock, LW_SHARED);
 	MySerializableXact->finishedBefore = XidFromFullTransactionId(TransamVariables->nextXid);
+	LWLockRelease(XidGenLock);
 
 	/*
 	 * If it's not a commit it's either a rollback or a read-only transaction
-- 
2.47.0