Merge pull request kubernetes#85386 from mikedanese/fixstresstest

cache.Expiring: fix stress test: it's not doing anything

Author: k8s-ci-robot

staging/src/k8s.io/apimachinery/pkg/util/cache/expiring.go

@@ -102,8 +102,8 @@ func (c *Expiring) Set(key interface{}, val interface{}, ttl time.Duration) {
 
 	heap.Push(&c.heap, &expiringHeapEntry{
 		key:        key,
-		generation: c.generation,
 		expiry:     expiry,
+		generation: c.generation,
 	})
 }
 
@@ -158,13 +158,13 @@ func (c *Expiring) gc(now time.Time) {
 
 type expiringHeapEntry struct {
 	key        interface{}
-	generation uint64
 	expiry     time.Time
+	generation uint64
 }
 
-// expiringHeap is a min-heap ordered by expiration time of it's entries. The
-// expiring cache uses this as a priority queue efficiently organize entries to
-// be garbage collected once they expire.
+// expiringHeap is a min-heap ordered by expiration time of its entries. The
+// expiring cache uses this as a priority queue to efficiently organize entries
+// which will be garbage collected once they expire.
 type expiringHeap []*expiringHeapEntry
 
 var _ heap.Interface = &expiringHeap{}

staging/src/k8s.io/apimachinery/pkg/util/cache/expiring_test.go

@@ -264,6 +264,7 @@ func TestStressExpiringCache(t *testing.T) {
 	for i := 0; i < 256; i++ {
 		wg.Add(1)
 		go func() {
+			defer wg.Done()
 			rand := rand.New(rand.NewSource(rand.Int63()))
 			for {
 				select {
@@ -273,11 +274,18 @@ func TestStressExpiringCache(t *testing.T) {
 				}
 				key := keys[rand.Intn(numKeys)]
 				if _, ok := cache.Get(key); !ok {
-					cache.Set(key, struct{}{}, time.Second)
+					cache.Set(key, struct{}{}, 50*time.Millisecond)
 				}
 			}
 		}()
 	}
 
-	wg.Done()
+	wg.Wait()
+
+	// trigger a GC with a set and check the cache size.
+	time.Sleep(60 * time.Millisecond)
+	cache.Set("trigger", "gc", time.Second)
+	if cache.Len() != 1 {
+		t.Errorf("unexpected cache size: got=%d, want=1", cache.Len())
+	}
 }