From cf03bc64622b22d515f18e868d1719d2240c9ffd Mon Sep 17 00:00:00 2001
From: Simon Riggs <simon@2ndQuadrant.com>
Date: Mon, 5 Oct 2009 14:52:36 +0100
Subject: [PATCH] Apply
 heikki1/0012-Don-t-hold-RecoveryInfoLock-over-lock-sleep.patch

---
 src/backend/storage/lmgr/lock.c | 31 ++++++++++++-------------------
 1 file changed, 12 insertions(+), 19 deletions(-)

diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 1e8fc2b7c8..73c3d66c15 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -567,24 +567,14 @@ LockAcquire(const LOCKTAG *locktag,
 	}
 
 	/*
-	 * Obtain the RecoveryInfoLock if we have a lock that needs to be
-	 * WAL logged. This ensures that we don't concurrently grab a lock
-	 * while we are preparing GetRunningTransactionData().
-	 * Make sure this definition matches IsProcLockLoggable(), which
-	 * is used to unset.
+	 * Decide if this is the kind of lock that needs to be WAL logged. Make
+	 * sure this definition matches IsProcLockLoggable(), which is used to
+	 * unset.
 	 */
 	if (!RecoveryInProgress() && XLogArchivingActive() &&
 		lockmode >= AccessExclusiveLock &&
 		locktag->locktag_type == LOCKTAG_RELATION)
 	{
-		if (dontWait)
-		{
-			/* Handle NOWAIT lock requests correctly */
-			if (!LWLockConditionalAcquire(RecoveryInfoLock, LW_SHARED))
-				return LOCKACQUIRE_NOT_AVAIL;
-		}
-		else
-			LWLockAcquire(RecoveryInfoLock, LW_SHARED);
 		logLockrequest = true;
 	}
 
@@ -613,8 +603,6 @@ LockAcquire(const LOCKTAG *locktag,
 	if (!lock)
 	{
 		LWLockRelease(partitionLock);
-		if (logLockrequest)
-			LWLockRelease(RecoveryInfoLock);
 		ereport(ERROR,
 				(errcode(ERRCODE_OUT_OF_MEMORY),
 				 errmsg("out of shared memory"),
@@ -681,8 +669,6 @@ LockAcquire(const LOCKTAG *locktag,
 				elog(PANIC, "lock table corrupted");
 		}
 		LWLockRelease(partitionLock);
-		if (logLockrequest)
-			LWLockRelease(RecoveryInfoLock);
 		ereport(ERROR,
 				(errcode(ERRCODE_OUT_OF_MEMORY),
 				 errmsg("out of shared memory"),
@@ -812,8 +798,6 @@ LockAcquire(const LOCKTAG *locktag,
 			Assert((lock->nRequested > 0) && (lock->requested[lockmode] >= 0));
 			Assert(lock->nGranted <= lock->nRequested);
 			LWLockRelease(partitionLock);
-			if (logLockrequest)
-				LWLockRelease(RecoveryInfoLock);
 			if (locallock->nLocks == 0)
 				RemoveLocalLock(locallock);
 			return LOCKACQUIRE_NOT_AVAIL;
@@ -878,6 +862,15 @@ LockAcquire(const LOCKTAG *locktag,
 		XLogRecData		rdata;
 		xl_rel_lock		xlrec;
 
+		/*
+		 * Ensure that if bgwriter is just making a snapshot of locks
+		 * and running-xacts, we won't write the WAL record until it's done.
+		 * In case the other process didn't see our lock in the lock table yet,
+		 * we want the XLOG_RELATION_LOCK WAL record to appear *after* the
+		 * running-xacts record.
+		 */
+		LWLockAcquire(RecoveryInfoLock, LW_SHARED);
+
 		/*
 		 * First thing we do is ensure that a TransactionId has been
 		 * assigned to this transaction. We don't actually need the xid yet
-- 
2.30.2