allocrunner: Drop and log updates after closing waitCh

client/allocrunner/alloc_runner.go

@@ -629,7 +629,15 @@ func (ar *allocRunner) Update(update *structs.Allocation) {
 				"new_modify_index", update.AllocModifyIndex)
 			ar.allocUpdatedCh <- oldUpdate
 			return
+		} else {
+			ar.logger.Trace("Discarding allocation update",
+				"skipped_modify_index", oldUpdate.AllocModifyIndex,
+				"new_modify_index", update.AllocModifyIndex)
 		}
+	case <-ar.waitCh:
+		ar.logger.Trace("AllocRunner has terminated, skipping alloc update",
+			"modify_index", update.AllocModifyIndex)
+		return
 	default:
 	}
 

client/allocrunner/alloc_runner_test.go

@@ -326,6 +326,15 @@ func TestAllocRunner_Update_Semantics(t *testing.T) {
 
 	queuedAlloc = <-ar.allocUpdatedCh
 	require.Equal(upd2, queuedAlloc)
+
+	// Ignore after watch closed
+
+	close(ar.waitCh)
+
+	ar.Update(upd1)
+
+	// Did not queue the update
+	require.Len(ar.allocUpdatedCh, 0)
 }
 
 /*