postgrespro.git / summary / log / commit / refs

commit    47a338cfcd67139a1f91892b080934fcfc3aea03
Author:   Thomas Munro <tmunro@postgresql.org>
Date:     Thu May 09 07:11:46 2019 +0000

    Fix SxactGlobalXmin tracking.
    
    Commit bb16aba50 broke the code that maintains SxactGlobalXmin.  It
    could get stuck when a well-timed READ ONLY transaction runs.  If
    SxactGlobalXmin stops advancing, transactions on the
    FinishedSerializableTransactions queue are never cleaned up, so
    resources are effectively leaked.  Revert that hunk of the commit.
    
    Also revert another similar hunk that was probably harmless, but
    unnecessary and unjustified, relating to the DOOMED flag in case of
    RO_SAFE early release.
    
    Author: Thomas Munro
    Reported-by: Tom Lane
    Discussion: https://postgr.es/m/16170.1557251214%40sss.pgh.pa.us


 src/backend/storage/lmgr/predicate.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index 4e4d04bae3..7f607b2bf8 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -3438,8 +3438,7 @@ ReleasePredicateLocks(bool isCommit, bool isReadOnlySafe)
 		 * cleanup. This means it should not be considered when calculating
 		 * SxactGlobalXmin.
 		 */
-		if (!isReadOnlySafe)
-			MySerializableXact->flags |= SXACT_FLAG_DOOMED;
+		MySerializableXact->flags |= SXACT_FLAG_DOOMED;
 		MySerializableXact->flags |= SXACT_FLAG_ROLLED_BACK;
 
 		/*
@@ -3635,8 +3634,7 @@ ReleasePredicateLocks(bool isCommit, bool isReadOnlySafe)
 	 * was launched.
 	 */
 	needToClear = false;
-	if (!isReadOnlySafe &&
-		TransactionIdEquals(MySerializableXact->xmin, PredXact->SxactGlobalXmin))
+	if (TransactionIdEquals(MySerializableXact->xmin, PredXact->SxactGlobalXmin))
 	{
 		Assert(PredXact->SxactGlobalXminCount > 0);
 		if (--(PredXact->SxactGlobalXminCount) == 0)


[parent: cd805f46d857]