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Posted to commits@zookeeper.apache.org by ma...@apache.org on 2009/08/04 19:59:58 UTC
svn commit: r800891 - in /hadoop/zookeeper/trunk: CHANGES.txt
src/java/main/org/apache/zookeeper/server/quorum/FastLeaderElection.java
src/java/test/org/apache/zookeeper/test/FLELostMessageTest.java
Author: mahadev
Date: Tue Aug 4 17:59:58 2009
New Revision: 800891
URL: http://svn.apache.org/viewvc?rev=800891&view=rev
Log:
ZOOKEEPER-480. FLE should perform leader check when node is not leading and add vote of follower (flavio via mahadev)
Added:
hadoop/zookeeper/trunk/src/java/test/org/apache/zookeeper/test/FLELostMessageTest.java
Modified:
hadoop/zookeeper/trunk/CHANGES.txt
hadoop/zookeeper/trunk/src/java/main/org/apache/zookeeper/server/quorum/FastLeaderElection.java
Modified: hadoop/zookeeper/trunk/CHANGES.txt
URL: http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/CHANGES.txt?rev=800891&r1=800890&r2=800891&view=diff
==============================================================================
--- hadoop/zookeeper/trunk/CHANGES.txt (original)
+++ hadoop/zookeeper/trunk/CHANGES.txt Tue Aug 4 17:59:58 2009
@@ -35,6 +35,9 @@
ZOOKEEPER-466. crash on zookeeper_close() when using auth with empty cert
(Chris Darroch via phunt)
+ ZOOKEEPER-480. FLE should perform leader check when node is not leading and
+ add vote of follower (flavio via mahadev)
+
IMPROVEMENTS:
ZOOKEEPER-473. cleanup junit tests to eliminate false positives due to
"socket reuse" and failure to close client (phunt via mahadev)
Modified: hadoop/zookeeper/trunk/src/java/main/org/apache/zookeeper/server/quorum/FastLeaderElection.java
URL: http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/src/java/main/org/apache/zookeeper/server/quorum/FastLeaderElection.java?rev=800891&r1=800890&r2=800891&view=diff
==============================================================================
--- hadoop/zookeeper/trunk/src/java/main/org/apache/zookeeper/server/quorum/FastLeaderElection.java (original)
+++ hadoop/zookeeper/trunk/src/java/main/org/apache/zookeeper/server/quorum/FastLeaderElection.java Tue Aug 4 17:59:58 2009
@@ -490,9 +490,20 @@
long epoch){
boolean predicate = true;
- if(votes.get(leader) == null) predicate = false;
- else if(votes.get(leader).state != ServerState.LEADING) predicate = false;
+
+ /*
+ * If everyone else thinks I'm the leader, I must be the leader.
+ * The other two checks are just for the case in which I'm not the
+ * leader. If I'm not the leader and I haven't received a message
+ * from leader stating that it is leading, then predicate is false.
+ */
+
+ if(leader != self.getId()){
+ if(votes.get(leader) == null) predicate = false;
+ else if(votes.get(leader).state != ServerState.LEADING) predicate = false;
+ }
+ //LOG.info("Leader predicate: " + predicate);
return predicate;
}
@@ -643,13 +654,18 @@
* this leader, then processes will naturally move
* to a new epoch.
*/
- if((n.state == ServerState.LEADING) &&
- (n.epoch == logicalclock)){
- self.setPeerState((n.leader == self.getId()) ?
- ServerState.LEADING: ServerState.FOLLOWING);
+ if(n.epoch == logicalclock){
+ recvset.put(n.sid, new Vote(n.leader, n.zxid, n.epoch));
+ if((n.state == ServerState.LEADING) ||
+ (termPredicate(recvset, new Vote(n.leader,
+ n.zxid, n.epoch, n.state))
+ && checkLeader(outofelection, n.leader, n.epoch)) ){
+ self.setPeerState((n.leader == self.getId()) ?
+ ServerState.LEADING: ServerState.FOLLOWING);
- leaveInstance();
- return new Vote(n.leader, n.zxid);
+ leaveInstance();
+ return new Vote(n.leader, n.zxid);
+ }
}
LOG.info("Notification: " + n.leader + ", " + n.zxid +
@@ -671,6 +687,7 @@
leaveInstance();
return new Vote(n.leader, n.zxid);
}
+
break;
}
}
Added: hadoop/zookeeper/trunk/src/java/test/org/apache/zookeeper/test/FLELostMessageTest.java
URL: http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/src/java/test/org/apache/zookeeper/test/FLELostMessageTest.java?rev=800891&view=auto
==============================================================================
--- hadoop/zookeeper/trunk/src/java/test/org/apache/zookeeper/test/FLELostMessageTest.java (added)
+++ hadoop/zookeeper/trunk/src/java/test/org/apache/zookeeper/test/FLELostMessageTest.java Tue Aug 4 17:59:58 2009
@@ -0,0 +1,196 @@
+/**
+ * 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 java.io.File;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.concurrent.Semaphore;
+
+import junit.framework.TestCase;
+
+import org.apache.log4j.Logger;
+import org.apache.zookeeper.PortAssignment;
+import org.apache.zookeeper.server.quorum.FastLeaderElection;
+import org.apache.zookeeper.server.quorum.QuorumCnxManager;
+import org.apache.zookeeper.server.quorum.QuorumPeer;
+import org.apache.zookeeper.server.quorum.Vote;
+import org.apache.zookeeper.server.quorum.QuorumPeer.QuorumServer;
+import org.apache.zookeeper.server.quorum.QuorumPeer.ServerState;
+import org.junit.Test;
+
+
+/**
+ * This test uses a mock server to interact with a ZooKeeper peer and
+ * reproduces a specific sequence of messages that can cause FLE to fail.
+ * In particular, it reproduces the following scenario:
+ *
+ * 1- We have an ensemble of 3 servers, but only two start;
+ * 2- Process 0 elects 1, but 1 fails to receive the message from 0
+ * stating that it changed its vote to 1;
+ * 3- The next from 0 that 1 receives is a notification that 0 is
+ * following 1. However, because 1 does not receive a notification
+ * from 0 while 0 is following, it may end up not becoming leader
+ * with old code.
+ *
+ * This test checks that this sequence of messages does not lead to a
+ * deadlock. In practice, even if this situation occurs in a run, it would
+ * have to occur continuously to prevent a leader from being elected
+ * forever. This happens with low probability.
+ *
+ */
+public class FLELostMessageTest extends TestCase {
+ protected static final Logger LOG = Logger.getLogger(FLELostMessageTest.class);
+
+
+ int count;
+ HashMap<Long,QuorumServer> peers;
+ File tmpdir[];
+ int port[];
+
+ QuorumCnxManager cnxManager;
+
+ @Override
+ public void setUp() throws Exception {
+ count = 3;
+
+ peers = new HashMap<Long,QuorumServer>(count);
+ tmpdir = new File[count];
+ port = new int[count];
+
+ LOG.info("SetUp " + getName());
+ }
+
+ @Override
+ public void tearDown() throws Exception {
+ cnxManager.halt();
+ LOG.info("FINISHED " + getName());
+ }
+
+
+ class LEThread extends Thread {
+ int i;
+ QuorumPeer peer;
+
+ LEThread(QuorumPeer peer, int i) {
+ this.i = i;
+ this.peer = peer;
+ LOG.info("Constructor: " + getName());
+
+ }
+
+ public void run(){
+ boolean flag = true;
+ try{
+ Vote v = null;
+ peer.setPeerState(ServerState.LOOKING);
+ LOG.info("Going to call leader election: " + i);
+ v = peer.getElectionAlg().lookForLeader();
+
+ if (v == null){
+ fail("Thread " + i + " got a null vote");
+ }
+
+ /*
+ * A real zookeeper would take care of setting the current vote. Here
+ * we do it manually.
+ */
+ peer.setCurrentVote(v);
+
+ LOG.info("Finished election: " + i + ", " + v.id);
+
+ assertTrue("State is not leading.", peer.getPeerState() == ServerState.LEADING);
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+ LOG.info("Joining");
+ }
+ }
+ @Test
+ public void testLostMessage() throws Exception {
+ FastLeaderElection le[] = new FastLeaderElection[count];
+
+ LOG.info("TestLE: " + getName()+ ", " + count);
+ for(int i = 0; i < count; i++) {
+ int clientport = PortAssignment.unique();
+ peers.put(Long.valueOf(i),
+ new QuorumServer(i,
+ new InetSocketAddress(clientport),
+ new InetSocketAddress(PortAssignment.unique())));
+ tmpdir[i] = ClientBase.createTmpDir();
+ port[i] = clientport;
+ }
+
+ /*
+ * Start server 0
+ */
+
+ QuorumPeer peer = new QuorumPeer(peers, tmpdir[1], tmpdir[1], port[1], 3, 1, 2, 2, 2);
+ peer.startLeaderElection();
+ LEThread thread = new LEThread(peer, 1);
+ thread.start();
+
+ /*
+ * Start mock server 1
+ */
+ mockServer();
+ thread.join(5000);
+ if (thread.isAlive()) {
+ fail("Threads didn't join");
+ }
+ }
+
+ ByteBuffer createMsg(int state, long leader, long zxid, long epoch){
+ byte requestBytes[] = new byte[28];
+ ByteBuffer requestBuffer = ByteBuffer.wrap(requestBytes);
+
+ /*
+ * Building notification packet to send
+ */
+
+ requestBuffer.clear();
+ requestBuffer.putInt(state);
+ requestBuffer.putLong(leader);
+ requestBuffer.putLong(zxid);
+ requestBuffer.putLong(epoch);
+
+ return requestBuffer;
+ }
+
+ void mockServer() throws InterruptedException, IOException {
+ /*
+ * Create an instance of the connection manager
+ */
+ QuorumPeer peer = new QuorumPeer(peers, tmpdir[0], tmpdir[0], port[0], 3, 0, 2, 2, 2);
+ cnxManager = new QuorumCnxManager(peer);
+ QuorumCnxManager.Listener listener = cnxManager.listener;
+ if(listener != null){
+ listener.start();
+ } else {
+ LOG.error("Null listener when initializing cnx manager");
+ }
+
+ cnxManager.toSend(new Long(1), createMsg(ServerState.LOOKING.ordinal(), 0, -1, 1));
+ cnxManager.recvQueue.take();
+ cnxManager.toSend(new Long(1), createMsg(ServerState.FOLLOWING.ordinal(), 1, -1, 1));
+ }
+}
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