Fix flaky TestBlocksCleaner by awaiting HeartBeat goroutine completion

Signed-off-by: Artem Muterko <artem@sopho.tech>

Author: archy-rock3t-cloud

CHANGELOG.md

@@ -50,6 +50,7 @@
 * [BUGFIX] Ring: Fix ring token conflict resolution only applied to updated instance and make constantly token conflict check during instance observe period.
 * [BUGFIX] Distributor: Fix a panic (`slice bounds out of range`) in the stream push path when the context deadline expires while the worker goroutine is still marshalling a `WriteRequest`. #7541
 * [BUGFIX] Query Frontend: Fix native histogram responses not being handled correctly in `minTime()` sort ordering for split_by_interval merge. #7555
+* [BUGFIX] Compactor: Ensure visit marker heartbeat goroutine completes before blocks cleaner returns. #7386
 
 ## 1.21.0 2026-04-24
 

pkg/compactor/blocks_cleaner.go

@@ -357,9 +357,14 @@ func (c *BlocksCleaner) cleanUpActiveUsers(ctx context.Context, users []string,
 			return nil
 		}
 		errChan := make(chan error, 1)
-		go visitMarkerManager.HeartBeat(ctx, errChan, c.cleanerVisitMarkerFileUpdateInterval, true)
+		doneChan := make(chan struct{})
+		go func() {
+			visitMarkerManager.HeartBeat(ctx, errChan, c.cleanerVisitMarkerFileUpdateInterval, true)
+			close(doneChan)
+		}()
 		defer func() {
 			errChan <- nil
+			<-doneChan
 		}()
 		return errors.Wrapf(c.cleanUser(ctx, userLogger, userBucket, userID, firstRun), "failed to delete blocks for user: %s", userID)
 	})
@@ -392,9 +397,14 @@ func (c *BlocksCleaner) cleanDeletedUsers(ctx context.Context, users []string) e
 			return nil
 		}
 		errChan := make(chan error, 1)
-		go visitMarkerManager.HeartBeat(ctx, errChan, c.cleanerVisitMarkerFileUpdateInterval, true)
+		doneChan := make(chan struct{})
+		go func() {
+			visitMarkerManager.HeartBeat(ctx, errChan, c.cleanerVisitMarkerFileUpdateInterval, true)
+			close(doneChan)
+		}()
 		defer func() {
 			errChan <- nil
+			<-doneChan
 		}()
 		return errors.Wrapf(c.deleteUserMarkedForDeletion(ctx, userLogger, userBucket, userID), "failed to delete user marked for deletion: %s", userID)
 	})