Allow mmap to run during head compaction

Signed-off-by: alanprot <alanprot@gmail.com>

tsdb/db.go

@@ -1057,9 +1057,26 @@ func (db *DB) Dir() string {
 
 func (db *DB) run(ctx context.Context) {
 	defer close(db.donec)
+	wg := sync.WaitGroup{}
+	wg.Add(1)
 
+	go func() {
+		defer wg.Done()
+		for {
+			select {
+			case <-db.stopc:
+				return
+			case <-time.After(1 * time.Minute):
+				// We attempt mmapping of head chunks regularly.
+				db.head.mmapHeadChunks()
+			}
+		}
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
 		backoff := time.Duration(0)
-
 		for {
 			select {
 			case <-db.stopc:
@@ -1079,8 +1096,6 @@ func (db *DB) run(ctx context.Context) {
 				case db.compactc <- struct{}{}:
 				default:
 				}
-			// We attempt mmapping of head chunks regularly.
-			db.head.mmapHeadChunks()
 			case <-db.compactc:
 				db.metrics.compactionsTriggered.Inc()
 
@@ -1100,6 +1115,9 @@ func (db *DB) run(ctx context.Context) {
 				return
 			}
 		}
+	}()
+
+	wg.Wait()
 }
 
 // Appender opens a new appender against the database.