>From 3f5bf1e2fad99081edfcb31601398af3b953cf15 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Thu, 13 Dec 2012 20:49:59 +0100 Subject: [PATCH 2/2] wal decoding: Use GetOldestXminNoLock to compute the initial logical xmin safely --- src/backend/replication/walsender.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c index c1ec0a3..2204c7a 100644 --- a/src/backend/replication/walsender.c +++ b/src/backend/replication/walsender.c @@ -544,16 +544,12 @@ InitLogicalReplication(InitLogicalReplicationCmd *cmd) * cannot go backwards anymore, as ComputeLogicalXmin() nails the value * down. * - * We need to do this *after* releasing the spinlock, otherwise - * GetOldestXmin will deadlock with ourselves. - * - * FIXME: think about solving the race conditions in a nicer way. + * FIXME: this should probably be in procarray.c? */ -recompute_xmin: - walsnd->xmin = GetOldestXmin(true, true); + LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE); + walsnd->xmin = GetOldestXminNoLock(true, true); + LWLockRelease(ProcArrayLock); ComputeLogicalXmin(); - if (walsnd->xmin != GetOldestXmin(true, true)) - goto recompute_xmin; decoding_ctx = AllocSetContextCreate(TopMemoryContext, "decoding context", @@ -1133,8 +1129,10 @@ ProcessStandbyReplyMessage(void) } /* - * Do an unlocked check for candidate_xmin first. + * Advance our local xmin horizin when the client confirmed a flush. */ + + /* Do an unlocked check for candidate_xmin first.*/ if (MyLogicalWalSnd && TransactionIdIsValid(MyLogicalWalSnd->candidate_xmin)) { -- 1.7.12.289.g0ce9864.dirty