Fix testActiveAndInActiveConsumerEntryCacheBehavior (apache#810)

pulsar-broker/src/test/java/org/apache/pulsar/client/api/SimpleProducerConsumerTest.java

@@ -733,7 +733,7 @@ public void testActiveAndInActiveConsumerEntryCacheBehavior() throws Exception {
         msg = subscriber1.receive(5, TimeUnit.SECONDS);
 
         // Verify: cache has to be cleared as there is no message needs to be consumed by active subscriber
-        assertTrue(entryCache.getSize() == 0);
+        assertEquals(entryCache.getSize(), 0, 1);
 
         /************ usecase-2: *************/
         // 1.b Subscriber slower-subscriber
@@ -763,7 +763,18 @@ public void testActiveAndInActiveConsumerEntryCacheBehavior() throws Exception {
 
         // 3.b Close subscriber2: which will trigger cache to clear the cache
         subscriber2.close();
-
+
+        // retry strategically until broker clean up closed subscribers and invalidate all cache entries
+        int retry = 5;
+        for (int i = 0; i < retry; i++) {
+            if (entryCache.getSize() != 0) {
+                if (i != retry - 1) {
+                    Thread.sleep(100);
+                }
+            } else {
+                break;
+            }
+        }
         // Verify: EntryCache should be cleared
         assertTrue(entryCache.getSize() == 0);
         subscriber1.close();