diff --git a/internal/datacoord/compaction.go b/internal/datacoord/compaction.go
index c1f58b94d414d..1b80d082bece2 100644
--- a/internal/datacoord/compaction.go
+++ b/internal/datacoord/compaction.go
@@ -214,6 +214,7 @@ func (c *compactionPlanHandler) schedule() []CompactionTask {
 
 	c.executingGuard.Lock()
 	if len(c.executingTasks) >= parallelism {
+		c.executingGuard.Unlock()
 		return selected
 	}
 	c.executingGuard.Unlock()