Applied K.Knizhnik's deadlock patch

Author: vbwagner

src/backend/storage/lmgr/proc.c

@@ -186,6 +186,7 @@ InitProcGlobal(void)
 	ProcGlobal->walwriterLatch = NULL;
 	ProcGlobal->checkpointerLatch = NULL;
 	pg_atomic_init_u32(&ProcGlobal->procArrayGroupFirst, INVALID_PGPROCNO);
+	pg_atomic_init_flag(&ProcGlobal->activeDeadlockCheck);
 
 	/*
 	 * Create and initialize all the PGPROC structures we'll need.  There are
@@ -1657,6 +1658,10 @@ CheckDeadLock(void)
 {
 	int			i;
 
+
+	if (!pg_atomic_test_set_flag(&ProcGlobal->activeDeadlockCheck))
+		return;
+
 	/*
 	 * Acquire exclusive lock on the entire shared lock data structures. Must
 	 * grab LWLocks in partition-number order to avoid LWLock deadlock.
@@ -1732,6 +1737,8 @@ CheckDeadLock(void)
 check_done:
 	for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
 		LWLockRelease(LockHashPartitionLockByIndex(i));
+
+	pg_atomic_clear_flag(&ProcGlobal->activeDeadlockCheck);
 }
 
 /*

src/include/storage/proc.h

@@ -253,6 +253,8 @@ typedef struct PROC_HDR
 	int			startupProcPid;
 	/* Buffer id of the buffer that Startup process waits for pin on, or -1 */
 	int			startupBufferPinWaitBufId;
+	/* Deadlock detection is in progress */
+	pg_atomic_flag activeDeadlockCheck;
 } PROC_HDR;
 
 extern PGDLLIMPORT PROC_HDR *ProcGlobal;