Merge #108797

108797: concurrency: only count active waiter in totalAndMaxWaitDuration metric calculation r=arulajmani a=lyang24

concurrency: only count active waiter in totalAndMaxWaitDuration metric calculation.
   
The lock wait duration should only apply for the waiters that are actively waiting. This change 
has no effect on wating readers since all waiting readers are active. We are excluding all 
inactive locking requests' wait time contribution to the total and max waiting duration.

Fixes: #108683
Release note: None.

Co-authored-by: Eric.Yang <[email protected]>

Author: craig[bot]

pkg/kv/kvserver/concurrency/lock_table.go

@@ -2152,7 +2152,7 @@ func (kl *keyLocks) lockHeldDuration(now time.Time) time.Duration {
 	return now.Sub(minStartTS)
 }
 
-// Returns the total amount of time all waiters in the queues of
+// Returns the total amount of time all active waiters in the queues of
 // readers and locking requests have been waiting on the key referenced in the
 // receiver.
 //
@@ -2172,14 +2172,16 @@ func (kl *keyLocks) totalAndMaxWaitDuration(now time.Time) (time.Duration, time.
 	}
 	for e := kl.queuedLockingRequests.Front(); e != nil; e = e.Next() {
 		qg := e.Value
-		g := qg.guard
-		g.mu.Lock()
-		waitDuration := now.Sub(g.mu.curLockWaitStart)
-		totalWaitDuration += waitDuration
-		if waitDuration > maxWaitDuration {
-			maxWaitDuration = waitDuration
+		if qg.active {
+			g := qg.guard
+			g.mu.Lock()
+			waitDuration := now.Sub(g.mu.curLockWaitStart)
+			totalWaitDuration += waitDuration
+			if waitDuration > maxWaitDuration {
+				maxWaitDuration = waitDuration
+			}
+			g.mu.Unlock()
 		}
-		g.mu.Unlock()
 	}
 	return totalWaitDuration, maxWaitDuration
 }