do async notification if there are too many clients to notify

apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/config/BizConfig.java

@@ -105,4 +105,11 @@ public class BizConfig extends RefreshableConfig {
     return TimeUnit.SECONDS;
   }
 
+  public int releaseMessageNotificationBatch() {
+    return getIntProperty("apollo.release-message.notification.batch", 100);
+  }
+
+  public int releaseMessageNotificationBatchIntervalInMilli() {
+    return getIntProperty("apollo.release-message.notification.batch.interval", 100);
+  }
 }

apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/controller/NotificationControllerV2.java

@@ -12,6 +12,7 @@ import com.google.common.collect.Sets;
 import com.google.gson.Gson;
 import com.google.gson.reflect.TypeToken;
 
+import com.ctrip.framework.apollo.biz.config.BizConfig;
 import com.ctrip.framework.apollo.biz.entity.ReleaseMessage;
 import com.ctrip.framework.apollo.biz.message.ReleaseMessageListener;
 import com.ctrip.framework.apollo.biz.message.Topics;
@@ -22,6 +23,7 @@ import com.ctrip.framework.apollo.configservice.util.NamespaceUtil;
 import com.ctrip.framework.apollo.configservice.util.WatchKeysUtil;
 import com.ctrip.framework.apollo.core.ConfigConsts;
 import com.ctrip.framework.apollo.core.dto.ApolloConfigNotification;
+import com.ctrip.framework.apollo.core.utils.ApolloThreadFactory;
 import com.ctrip.framework.apollo.tracer.Tracer;
 
 import org.slf4j.Logger;
@@ -41,6 +43,9 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
 
 /**
  * @author Jason Song(song_s@ctrip.com)
@@ -61,6 +66,8 @@ public class NotificationControllerV2 implements ReleaseMessageListener {
       new TypeToken<List<ApolloConfigNotification>>() {
       }.getType();
 
+  private final ExecutorService largeNotificationBatchExecutorService;
+
   @Autowired
   private WatchKeysUtil watchKeysUtil;
 
@@ -76,6 +83,14 @@ public class NotificationControllerV2 implements ReleaseMessageListener {
   @Autowired
   private Gson gson;
 
+  @Autowired
+  private BizConfig bizConfig;
+
+  public NotificationControllerV2() {
+    largeNotificationBatchExecutorService = Executors.newSingleThreadExecutor(ApolloThreadFactory.create
+        ("NotificationControllerV2", true));
+  }
+
   @RequestMapping(method = RequestMethod.GET)
   public DeferredResult<ResponseEntity<List<ApolloConfigNotification>>> pollNotification(
       @RequestParam(value = "appId") String appId,
@@ -220,6 +235,27 @@ public class NotificationControllerV2 implements ReleaseMessageListener {
     //create a new list to avoid ConcurrentModificationException
     List<DeferredResult<ResponseEntity<List<ApolloConfigNotification>>>> results =
         Lists.newArrayList(deferredResults.get(content));
+
+    //do async notification if too many clients
+    if (results.size() > bizConfig.releaseMessageNotificationBatch()) {
+      largeNotificationBatchExecutorService.submit(() -> {
+        logger.debug("Async notify {} clients for key {} with batch {}", results.size(), content,
+            bizConfig.releaseMessageNotificationBatch());
+        for (int i = 0; i < results.size(); i++) {
+          if (i > 0 && i % bizConfig.releaseMessageNotificationBatch() == 0) {
+            try {
+              TimeUnit.MILLISECONDS.sleep(bizConfig.releaseMessageNotificationBatchIntervalInMilli());
+            } catch (InterruptedException e) {
+              //ignore
+            }
+          }
+          logger.debug("Async notify {}", results.get(i));
+          results.get(i).setResult(notification);
+        }
+      });
+      return;
+    }
+
     logger.debug("Notify {} clients for key {}", results.size(), content);
 
     for (DeferredResult<ResponseEntity<List<ApolloConfigNotification>>> result : results) {

apollo-configservice/src/test/java/com/ctrip/framework/apollo/configservice/controller/NotificationControllerV2Test.java

@@ -7,6 +7,7 @@ import com.google.common.collect.Multimap;
 import com.google.common.collect.Sets;
 import com.google.gson.Gson;
 
+import com.ctrip.framework.apollo.biz.config.BizConfig;
 import com.ctrip.framework.apollo.biz.entity.ReleaseMessage;
 import com.ctrip.framework.apollo.biz.message.Topics;
 import com.ctrip.framework.apollo.biz.utils.EntityManagerUtil;
@@ -27,6 +28,7 @@ import org.springframework.test.util.ReflectionTestUtils;
 import org.springframework.web.context.request.async.DeferredResult;
 
 import java.util.List;
+import java.util.concurrent.TimeUnit;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
@@ -57,6 +59,9 @@ public class NotificationControllerV2Test {
   private NamespaceUtil namespaceUtil;
   @Mock
   private WatchKeysUtil watchKeysUtil;
+  @Mock
+  private BizConfig bizConfig;
+
   private Gson gson;
 
   private Multimap<String, DeferredResult<ResponseEntity<List<ApolloConfigNotification>>>>
@@ -66,11 +71,16 @@ public class NotificationControllerV2Test {
   public void setUp() throws Exception {
     controller = new NotificationControllerV2();
     gson = new Gson();
+
+    when(bizConfig.releaseMessageNotificationBatch()).thenReturn(100);
+    when(bizConfig.releaseMessageNotificationBatchIntervalInMilli()).thenReturn(5);
+
     ReflectionTestUtils.setField(controller, "releaseMessageService", releaseMessageService);
     ReflectionTestUtils.setField(controller, "entityManagerUtil", entityManagerUtil);
     ReflectionTestUtils.setField(controller, "namespaceUtil", namespaceUtil);
     ReflectionTestUtils.setField(controller, "watchKeysUtil", watchKeysUtil);
     ReflectionTestUtils.setField(controller, "gson", gson);
+    ReflectionTestUtils.setField(controller, "bizConfig", bizConfig);
 
     someAppId = "someAppId";
     someCluster = "someCluster";
@@ -283,6 +293,48 @@ public class NotificationControllerV2Test {
     assertEquals(someId, notification.getNotificationId());
   }
 
+  @Test
+  public void testPollNotificationWithHandleMessageInBatch() throws Exception {
+    String someWatchKey = Joiner.on(ConfigConsts.CLUSTER_NAMESPACE_SEPARATOR)
+        .join(someAppId, someCluster, defaultNamespace);
+    int someBatch = 1;
+    int someBatchInterval = 10;
+
+    Multimap<String, String> watchKeysMap =
+        assembleMultiMap(defaultNamespace, Lists.newArrayList(someWatchKey));
+
+    String notificationAsString =
+        transformApolloConfigNotificationsToString(defaultNamespace, someNotificationId);
+
+    when(watchKeysUtil
+        .assembleAllWatchKeys(someAppId, someCluster, Sets.newHashSet(defaultNamespace),
+            someDataCenter)).thenReturn(watchKeysMap);
+
+    when(bizConfig.releaseMessageNotificationBatch()).thenReturn(someBatch);
+    when(bizConfig.releaseMessageNotificationBatchIntervalInMilli()).thenReturn(someBatchInterval);
+
+    DeferredResult<ResponseEntity<List<ApolloConfigNotification>>>
+        deferredResult = controller
+        .pollNotification(someAppId, someCluster, notificationAsString, someDataCenter,
+            someClientIp);
+    DeferredResult<ResponseEntity<List<ApolloConfigNotification>>>
+        anotherDeferredResult = controller
+        .pollNotification(someAppId, someCluster, notificationAsString, someDataCenter,
+            someClientIp);
+
+    long someId = 1;
+    ReleaseMessage someReleaseMessage = new ReleaseMessage(someWatchKey);
+    someReleaseMessage.setId(someId);
+
+    controller.handleMessage(someReleaseMessage, Topics.APOLLO_RELEASE_TOPIC);
+
+    assertTrue(!anotherDeferredResult.hasResult());
+
+    TimeUnit.MILLISECONDS.sleep(someBatchInterval * 3);
+
+    assertTrue(anotherDeferredResult.hasResult());
+  }
+
   private String transformApolloConfigNotificationsToString(
       String namespace, long notificationId) {
     List<ApolloConfigNotification> notifications =