ZOOKEEPER-1294. One of the zookeeper server is not accepting any requests (Kavita Sharma via henryr)

git-svn-id: https://svn.apache.org/repos/asf/zookeeper/trunk@1231389 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -94,6 +94,8 @@ BUGFIXES:
 
   ZOOKEEPER-1050. zooinspector shell scripts do not work
   (Will Johnson via phunt)
+
+  ZOOKEEPER-1294. One of the zookeeper server is not accepting any requests (Kavita Sharma via henryr)
  
 IMPROVEMENTS:
 

src/java/main/org/apache/zookeeper/server/quorum/Leader.java

@@ -308,7 +308,7 @@ public class Leader {
             cnxAcceptor.setName("LearnerCnxAcceptor-" + ss.getLocalSocketAddress());
             cnxAcceptor.start();
 
-            long epoch = getEpochToPropose(self.getId(), self.getAcceptedEpoch());            
+            long epoch = getEpochToPropose(self.getId(), self.getAcceptedEpoch());
 
             zk.setZxid(ZxidUtils.makeZxid(epoch, 0));
 
@@ -377,15 +377,15 @@ public class Leader {
                 if (!tickSkip) {
                     self.tick++;
                 }
-                int syncedCount = 0;
                 HashSet<Long> syncedSet = new HashSet<Long>();
 
                 // lock on the followers when we use it.
                 syncedSet.add(self.getId());
                 synchronized (learners) {
                     for (LearnerHandler f : learners) {
-                        if (f.synced()) {
-                            syncedCount++;
+                        // Synced set is used to check we have a supporting quorum, so only
+                        // PARTICIPANT, not OBSERVER, learners should be used
+                        if (f.synced() && f.getLearnerType() == LearnerType.PARTICIPANT) {
                             syncedSet.add(f.getSid());
                         }
                         f.ping();
@@ -395,7 +395,7 @@ public class Leader {
                 //if (!tickSkip && syncedCount < self.quorumPeers.size() / 2) {
                     // Lost quorum, shutdown
                   // TODO: message is wrong unless majority quorums used
-                    shutdown("Only " + syncedCount + " followers, need "
+                    shutdown("Only " + syncedSet.size() + " followers, need "
                             + (self.getVotingView().size() / 2));
                     // make sure the order is the same!
                     // the leader goes to looking
@@ -770,7 +770,7 @@ public class Leader {
             }
             connectingFollowers.add(sid);
             QuorumVerifier verifier = self.getQuorumVerifier();
-            if (connectingFollowers.contains(self.getId()) && 
+            if (connectingFollowers.contains(self.getId()) &&
                                             verifier.containsQuorum(connectingFollowers)) {
                 waitingForNewEpoch = false;
                 self.setAcceptedEpoch(epoch);

src/java/test/org/apache/zookeeper/test/ClientBase.java

@@ -53,6 +53,8 @@ import org.apache.zookeeper.server.ServerCnxnFactoryAccessor;
 import org.apache.zookeeper.server.ZKDatabase;
 import org.apache.zookeeper.server.ZooKeeperServer;
 import org.apache.zookeeper.server.persistence.FileTxnLog;
+import org.apache.zookeeper.server.quorum.QuorumPeer;
+
 import static org.apache.zookeeper.client.FourLetterWordMain.send4LetterWord;
 import org.junit.After;
 import org.junit.Assert;
@@ -263,6 +265,23 @@ public abstract class ClientBase extends ZKTestCase {
         return false;
     }
 
+    public static boolean waitForServerState(QuorumPeer qp, int timeout,
+            String serverState) {
+        long start = System.currentTimeMillis();
+        while (true) {
+            try {
+                Thread.sleep(250);
+            } catch (InterruptedException e) {
+                // ignore
+            }
+            if (qp.getServerState().equals(serverState))
+                return true;
+            if (System.currentTimeMillis() > start + timeout) {
+                return false;
+            }
+        }
+    }
+
     static void verifyThreadTerminated(Thread thread, long millis)
         throws InterruptedException
     {

src/java/test/org/apache/zookeeper/test/ObserverLETest.java

@@ -0,0 +1,76 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.zookeeper.test;
+
+import static org.junit.Assert.*;
+
+import java.util.Arrays;
+
+import org.apache.zookeeper.ZKTestCase;
+import org.apache.zookeeper.server.quorum.QuorumPeer;
+import org.apache.zookeeper.server.quorum.QuorumStats;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ObserverLETest extends ZKTestCase {
+    final QuorumBase qb = new QuorumBase();
+    final ClientTest ct = new ClientTest();
+
+    @Before
+    public void establishThreeParticipantOneObserverEnsemble() throws Exception {
+        qb.setUp(true);
+        ct.hostPort = qb.hostPort;
+        ct.setUpAll();
+        qb.s5.shutdown();
+    }
+
+    @After
+    public void shutdownQuorum() throws Exception {
+        ct.tearDownAll();
+        qb.tearDown();
+    }
+
+    /**
+     * See ZOOKEEPER-1294. Confirms that an observer will not support the quorum
+     * of a leader by forming a 5-node, 2-observer ensemble (so quorum size is 2).
+     * When all but the leader and one observer are shut down, the leader should
+     * enter the 'looking' state, not stay in the 'leading' state.
+     */
+    @Test
+    public void testLEWithObserver() throws Exception {
+        QuorumPeer leader = null;
+        for (QuorumPeer server : Arrays.asList(qb.s1, qb.s2, qb.s3)) {
+            if (server.getServerState().equals(
+                    QuorumStats.Provider.FOLLOWING_STATE)) {
+                server.shutdown();
+                assertTrue("Waiting for server down", ClientBase
+                        .waitForServerDown("127.0.0.1:"
+                                + server.getClientPort(),
+                                ClientBase.CONNECTION_TIMEOUT));
+            } else {
+                assertNull("More than one leader found", leader);
+                leader = server;
+            }
+        }
+        assertTrue("Leader is not in Looking state", ClientBase
+                .waitForServerState(leader, ClientBase.CONNECTION_TIMEOUT,
+                        QuorumStats.Provider.LOOKING_STATE));
+    }
+
+}