Revert "Display the time when the process started waiting for the lock, in pg_locks."

This reverts commit 3b733fcd04.

Per buildfarm members prion and rorqual.

contrib/amcheck/expected/check_btree.out

@@ -97,8 +97,8 @@ SELECT bt_index_parent_check('bttest_b_idx');
 SELECT * FROM pg_locks
 WHERE relation = ANY(ARRAY['bttest_a', 'bttest_a_idx', 'bttest_b', 'bttest_b_idx']::regclass[])
     AND pid = pg_backend_pid();
- locktype | database | relation | page | tuple | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | mode | granted | fastpath | waitstart 
-----------+----------+----------+------+-------+------------+---------------+---------+-------+----------+--------------------+-----+------+---------+----------+-----------
+ locktype | database | relation | page | tuple | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | mode | granted | fastpath 
+----------+----------+----------+------+-------+------------+---------------+---------+-------+----------+--------------------+-----+------+---------+----------
 (0 rows)
 
 COMMIT;

doc/src/sgml/catalogs.sgml

@@ -10604,19 +10604,6 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
        lock table
       </para></entry>
      </row>
-
-     <row>
-      <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>waitstart</structfield> <type>timestamptz</type>
-      </para>
-      <para>
-       Time when the server process started waiting for this lock,
-       or null if the lock is held.
-       Note that this can be null for a very short period of time after
-       the wait started even though <structfield>granted</structfield>
-       is <literal>false</literal>.
-      </para></entry>
-     </row>
     </tbody>
    </tgroup>
   </table>

src/backend/storage/ipc/standby.c

@@ -540,34 +540,12 @@ void
 ResolveRecoveryConflictWithLock(LOCKTAG locktag, bool logging_conflict)
 {
 	TimestampTz ltime;
-	TimestampTz now;
 
 	Assert(InHotStandby);
 
 	ltime = GetStandbyLimitTime();
-	now = GetCurrentTimestamp();
 
-	/*
-	 * Update waitStart if first time through after the startup process
-	 * started waiting for the lock. It should not be updated every time
-	 * ResolveRecoveryConflictWithLock() is called during the wait.
-	 *
-	 * Use the current time obtained for comparison with ltime as waitStart
-	 * (i.e., the time when this process started waiting for the lock). Since
-	 * getting the current time newly can cause overhead, we reuse the
-	 * already-obtained time to avoid that overhead.
-	 *
-	 * Note that waitStart is updated without holding the lock table's
-	 * partition lock, to avoid the overhead by additional lock acquisition.
-	 * This can cause "waitstart" in pg_locks to become NULL for a very short
-	 * period of time after the wait started even though "granted" is false.
-	 * This is OK in practice because we can assume that users are likely to
-	 * look at "waitstart" when waiting for the lock for a long time.
-	 */
-	if (pg_atomic_read_u64(&MyProc->waitStart) == 0)
-		pg_atomic_write_u64(&MyProc->waitStart, now);
-
-	if (now >= ltime && ltime != 0)
+	if (GetCurrentTimestamp() >= ltime && ltime != 0)
 	{
 		/*
 		 * We're already behind, so clear a path as quickly as possible.

src/backend/storage/lmgr/lock.c

@@ -3619,12 +3619,6 @@ GetLockStatusData(void)
 			instance->leaderPid = proc->pid;
 			instance->fastpath = true;
 
-			/*
-			 * Successfully taking fast path lock means there were no
-			 * conflicting locks.
-			 */
-			instance->waitStart = 0;
-
 			el++;
 		}
 
@@ -3652,7 +3646,6 @@ GetLockStatusData(void)
 			instance->pid = proc->pid;
 			instance->leaderPid = proc->pid;
 			instance->fastpath = true;
-			instance->waitStart = 0;
 
 			el++;
 		}
@@ -3705,7 +3698,6 @@ GetLockStatusData(void)
 		instance->pid = proc->pid;
 		instance->leaderPid = proclock->groupLeader->pid;
 		instance->fastpath = false;
-		instance->waitStart = (TimestampTz) pg_atomic_read_u64(&proc->waitStart);
 
 		el++;
 	}

src/backend/storage/lmgr/proc.c

@@ -402,7 +402,6 @@ InitProcess(void)
 	MyProc->lwWaitMode = 0;
 	MyProc->waitLock = NULL;
 	MyProc->waitProcLock = NULL;
-	pg_atomic_init_u64(&MyProc->waitStart, 0);
 #ifdef USE_ASSERT_CHECKING
 	{
 		int			i;
@@ -1263,23 +1262,6 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 		}
 		else
 			enable_timeout_after(DEADLOCK_TIMEOUT, DeadlockTimeout);
-
-		/*
-		 * Use the current time obtained for the deadlock timeout timer as
-		 * waitStart (i.e., the time when this process started waiting for the
-		 * lock). Since getting the current time newly can cause overhead, we
-		 * reuse the already-obtained time to avoid that overhead.
-		 *
-		 * Note that waitStart is updated without holding the lock table's
-		 * partition lock, to avoid the overhead by additional lock
-		 * acquisition. This can cause "waitstart" in pg_locks to become NULL
-		 * for a very short period of time after the wait started even though
-		 * "granted" is false. This is OK in practice because we can assume
-		 * that users are likely to look at "waitstart" when waiting for the
-		 * lock for a long time.
-		 */
-		pg_atomic_write_u64(&MyProc->waitStart,
-							get_timeout_start_time(DEADLOCK_TIMEOUT));
 	}
 	else if (log_recovery_conflict_waits)
 	{
@@ -1696,7 +1678,6 @@ ProcWakeup(PGPROC *proc, ProcWaitStatus waitStatus)
 	proc->waitLock = NULL;
 	proc->waitProcLock = NULL;
 	proc->waitStatus = waitStatus;
-	pg_atomic_write_u64(&MyProc->waitStart, 0);
 
 	/* And awaken it */
 	SetLatch(&proc->procLatch);

src/backend/utils/adt/lockfuncs.c

@@ -63,7 +63,7 @@ typedef struct
 } PG_Lock_Status;
 
 /* Number of columns in pg_locks output */
-#define NUM_LOCK_STATUS_COLUMNS		16
+#define NUM_LOCK_STATUS_COLUMNS		15
 
 /*
  * VXIDGetDatum - Construct a text representation of a VXID
@@ -142,8 +142,6 @@ pg_lock_status(PG_FUNCTION_ARGS)
 						   BOOLOID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 15, "fastpath",
 						   BOOLOID, -1, 0);
-		TupleDescInitEntry(tupdesc, (AttrNumber) 16, "waitstart",
-						   TIMESTAMPTZOID, -1, 0);
 
 		funcctx->tuple_desc = BlessTupleDesc(tupdesc);
 
@@ -338,10 +336,6 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		values[12] = CStringGetTextDatum(GetLockmodeName(instance->locktag.locktag_lockmethodid, mode));
 		values[13] = BoolGetDatum(granted);
 		values[14] = BoolGetDatum(instance->fastpath);
-		if (!granted && instance->waitStart != 0)
-			values[15] = TimestampTzGetDatum(instance->waitStart);
-		else
-			nulls[15] = true;
 
 		tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
 		result = HeapTupleGetDatum(tuple);
@@ -412,7 +406,6 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		values[12] = CStringGetTextDatum("SIReadLock");
 		values[13] = BoolGetDatum(true);
 		values[14] = BoolGetDatum(false);
-		nulls[15] = true;
 
 		tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
 		result = HeapTupleGetDatum(tuple);

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202102091
+#define CATALOG_VERSION_NO	202102021
 
 #endif

src/include/catalog/pg_proc.dat

@@ -5994,9 +5994,9 @@
 { oid => '1371', descr => 'view system lock information',
   proname => 'pg_lock_status', prorows => '1000', proretset => 't',
   provolatile => 'v', prorettype => 'record', proargtypes => '',
-  proallargtypes => '{text,oid,oid,int4,int2,text,xid,oid,oid,int2,text,int4,text,bool,bool,timestamptz}',
-  proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{locktype,database,relation,page,tuple,virtualxid,transactionid,classid,objid,objsubid,virtualtransaction,pid,mode,granted,fastpath,waitstart}',
+  proallargtypes => '{text,oid,oid,int4,int2,text,xid,oid,oid,int2,text,int4,text,bool,bool}',
+  proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{locktype,database,relation,page,tuple,virtualxid,transactionid,classid,objid,objsubid,virtualtransaction,pid,mode,granted,fastpath}',
   prosrc => 'pg_lock_status' },
 { oid => '2561',
   descr => 'get array of PIDs of sessions blocking specified backend PID from acquiring a heavyweight lock',

src/include/storage/lock.h

@@ -22,7 +22,6 @@
 #include "storage/lockdefs.h"
 #include "storage/lwlock.h"
 #include "storage/shmem.h"
-#include "utils/timestamp.h"
 
 /* struct PGPROC is declared in proc.h, but must forward-reference it */
 typedef struct PGPROC PGPROC;
@@ -447,8 +446,6 @@ typedef struct LockInstanceData
 	LOCKMODE	waitLockMode;	/* lock awaited by this PGPROC, if any */
 	BackendId	backend;		/* backend ID of this PGPROC */
 	LocalTransactionId lxid;	/* local transaction ID of this PGPROC */
-	TimestampTz waitStart;		/* time at which this PGPROC started waiting
-								 * for lock */
 	int			pid;			/* pid of this PGPROC */
 	int			leaderPid;		/* pid of group leader; = pid if no group */
 	bool		fastpath;		/* taken via fastpath? */

src/include/storage/proc.h

@@ -181,8 +181,6 @@ struct PGPROC
 	LOCKMODE	waitLockMode;	/* type of lock we're waiting for */
 	LOCKMASK	heldLocks;		/* bitmask for lock types already held on this
 								 * lock object by this backend */
-	pg_atomic_uint64 waitStart; /* time at which wait for lock acquisition
-								 * started */
 
 	bool		delayChkpt;		/* true if this proc delays checkpoint start */
 

src/test/regress/expected/rules.out

@@ -1394,9 +1394,8 @@ pg_locks| SELECT l.locktype,
     l.pid,
     l.mode,
     l.granted,
-    l.fastpath,
-    l.waitstart
-   FROM pg_lock_status() l(locktype, database, relation, page, tuple, virtualxid, transactionid, classid, objid, objsubid, virtualtransaction, pid, mode, granted, fastpath, waitstart);
+    l.fastpath
+   FROM pg_lock_status() l(locktype, database, relation, page, tuple, virtualxid, transactionid, classid, objid, objsubid, virtualtransaction, pid, mode, granted, fastpath);
 pg_matviews| SELECT n.nspname AS schemaname,
     c.relname AS matviewname,
     pg_get_userbyid(c.relowner) AS matviewowner,