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ZOOKEEPER-4785: Txn loss due to race condition in Learner.syncWithLea…
…der() during DIFF sync (#2111) (#2133) Author: Li Wang <[email protected]> Co-authored-by: liwang <[email protected]>
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zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/DIFFSyncTest.java
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| /* | ||
| * 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. | ||
| */ | ||
|
|
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| package org.apache.zookeeper.server.quorum; | ||
|
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| import static org.apache.zookeeper.test.ClientBase.CONNECTION_TIMEOUT; | ||
| import static org.junit.jupiter.api.Assertions.assertEquals; | ||
| import static org.junit.jupiter.api.Assertions.assertNotNull; | ||
| import static org.junit.jupiter.api.Assertions.assertTrue; | ||
| import java.io.IOException; | ||
| import java.util.ArrayList; | ||
| import java.util.List; | ||
| import javax.security.sasl.SaslException; | ||
| import org.apache.zookeeper.CreateMode; | ||
| import org.apache.zookeeper.PortAssignment; | ||
| import org.apache.zookeeper.ZooDefs; | ||
| import org.apache.zookeeper.ZooKeeper; | ||
| import org.apache.zookeeper.server.FinalRequestProcessor; | ||
| import org.apache.zookeeper.server.Request; | ||
| import org.apache.zookeeper.server.RequestProcessor; | ||
| import org.apache.zookeeper.server.SyncRequestProcessor; | ||
| import org.apache.zookeeper.server.ZooKeeperServer; | ||
| import org.apache.zookeeper.server.ZooKeeperServerListener; | ||
| import org.apache.zookeeper.server.persistence.FileTxnSnapLog; | ||
| import org.apache.zookeeper.test.ClientBase; | ||
| import org.junit.jupiter.api.AfterEach; | ||
| import org.junit.jupiter.api.BeforeEach; | ||
| import org.junit.jupiter.api.Test; | ||
| import org.junit.jupiter.api.Timeout; | ||
|
|
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| public class DIFFSyncTest extends QuorumPeerTestBase { | ||
| private static final int SERVER_COUNT = 3; | ||
| private static final String PATH_PREFIX = "/test_"; | ||
|
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| private int[] clientPorts; | ||
| private MainThread[] mt; | ||
| private ZooKeeper[] zkClients; | ||
|
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| @BeforeEach | ||
| public void start() throws Exception { | ||
| clientPorts = new int[SERVER_COUNT]; | ||
| mt = startQuorum(clientPorts); | ||
| zkClients = new ZooKeeper[SERVER_COUNT]; | ||
| } | ||
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| @AfterEach | ||
| public void tearDown() throws Exception{ | ||
| for (final ZooKeeper zk : zkClients) { | ||
| try { | ||
| if (zk != null) { | ||
| zk.close(); | ||
| } | ||
| } catch (final InterruptedException e) { | ||
| LOG.warn("ZooKeeper interrupted while shutting it down", e); | ||
| } | ||
| } | ||
|
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| for (final MainThread mainThread : mt) { | ||
| try { | ||
| mainThread.shutdown(); | ||
| } catch (final InterruptedException e) { | ||
| LOG.warn("Quorum Peer interrupted while shutting it down", e); | ||
| } | ||
| } | ||
| } | ||
|
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| @Test | ||
| @Timeout(value = 120) | ||
| public void testTxnLoss_FailToPersistAndCommitTxns() throws Exception { | ||
| final List<String> paths = new ArrayList<>(); | ||
| assertEquals(2, mt[2].getQuorumPeer().getLeaderId()); | ||
|
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| // create a ZK client to the leader (currentEpoch=1, lastLoggedZxid=<1, 1>) | ||
| createZKClient(2); | ||
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| // create a znode (currentEpoch=1, lastLoggedZxid=<1, 2>) | ||
| paths.add(createNode(zkClients[2], PATH_PREFIX + "0")); | ||
|
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| // shut down S0 | ||
| mt[0].shutdown(); | ||
| LOG.info("S0 shutdown."); | ||
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| // create a znode (currentEpoch=1, lastLoggedZxid=<1, 3>), so S0 is 1 txn behind | ||
| paths.add(createNode(zkClients[2], PATH_PREFIX + "1")); | ||
| logEpochsAndLastLoggedTxnForAllServers(); | ||
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| // shut down S1 | ||
| mt[1].shutdown(); | ||
| LOG.info("S1 shutdown."); | ||
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| // restart S0 and trigger a new leader election (currentEpoch=2) | ||
| // S0 starts with MockSyncRequestProcessor and MockCommitProcessor to simulate it writes the | ||
| // currentEpoch and sends NEWLEADER ACK but fails to persist and commit txns afterwards | ||
| // in DIFF sync | ||
| mt[0].start(new MockTestQPMain()); | ||
| assertTrue(ClientBase.waitForServerUp("127.0.0.1:" + clientPorts[0], CONNECTION_TIMEOUT), | ||
| "waiting for server 0 being up"); | ||
| LOG.info("S0 restarted."); | ||
| logEpochsAndLastLoggedTxnForAllServers(); | ||
|
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| // validate S2 is still the leader | ||
| assertEquals(2, mt[2].getQuorumPeer().getLeaderId()); | ||
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| // shut down the leader (i.e. S2). This causes S0 disconnects from leader, performs partial | ||
| // shutdown, fast forwards its database to the latest persisted tnx (i.e. <1, 3>) and change | ||
| // its state to LOOKING | ||
| mt[2].shutdown(); | ||
| LOG.info("S2 shutdown."); | ||
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| // start S1 and trigger a leader election (currentEpoch=3) | ||
| mt[1].start(); | ||
| assertTrue(ClientBase.waitForServerUp("127.0.0.1:" + clientPorts[1], CONNECTION_TIMEOUT), | ||
| "waiting for server 1 being up"); | ||
| LOG.info("S1 restarted."); | ||
| logEpochsAndLastLoggedTxnForAllServers(); | ||
|
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| // validate S0 is the new leader because of it has higher epoch | ||
| assertEquals(0, mt[0].getQuorumPeer().getLeaderId()); | ||
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| // connect to the new leader (i.e. S0) (currentEpoch=3, lastLoggedZxid=<3, 1> | ||
| createZKClient(0); | ||
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| // create a znode (currentEpoch=3, lastLoggedZxid=<3, 2>) | ||
| paths.add(createNode(zkClients[0], PATH_PREFIX + "3")); | ||
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| // start S2 which is the old leader | ||
| mt[2].start(); | ||
| assertTrue(ClientBase.waitForServerUp("127.0.0.1:" + clientPorts[2], CONNECTION_TIMEOUT), | ||
| "waiting for server " + 2 + " being up"); | ||
| LOG.info("S2 restarted."); | ||
| logEpochsAndLastLoggedTxnForAllServers(); | ||
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| // validate all the znodes exist from all the clients | ||
| validateDataFromAllClients(paths); | ||
| } | ||
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| @Test | ||
| @Timeout(value = 120) | ||
| public void testLeaderShutdown_AckProposalBeforeAckNewLeader() throws Exception { | ||
| assertEquals(2, mt[2].getQuorumPeer().getLeaderId()); | ||
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| // create a ZK client to the leader (currentEpoch=1, lastLoggedZxid=<1, 1>) | ||
| createZKClient(2); | ||
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| // create a znode (currentEpoch=1, lastLoggedZxid=<1, 2>) | ||
| createNode(zkClients[2], PATH_PREFIX + "0"); | ||
|
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| // shut down S0 | ||
| mt[0].shutdown(); | ||
| LOG.info("S0 shutdown."); | ||
|
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| // create a znode (currentEpoch=1, lastLoggedZxid=<1, 3>), so S0 is 1 txn behind | ||
| createNode(zkClients[2], PATH_PREFIX + "1"); | ||
| logEpochsAndLastLoggedTxnForAllServers(); | ||
|
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| // shut down S1 | ||
| mt[1].shutdown(); | ||
| LOG.info("S1 shutdown."); | ||
|
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| // restart S0 and trigger a new leader election and DIFF sync (currentEpoch=2) | ||
| mt[0].start(); | ||
| assertTrue(ClientBase.waitForServerUp("127.0.0.1:" + clientPorts[0], CONNECTION_TIMEOUT), | ||
| "waiting for server 0 being up"); | ||
| LOG.info("S0 restarted."); | ||
|
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| // create a znode (currentEpoch=2, lastLoggedZxid=<2, 1>) | ||
| createNode(zkClients[2], PATH_PREFIX + "2"); | ||
|
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| // validate quorum is up without additional round of leader election | ||
| for (int i = 0; i < SERVER_COUNT; i++) { | ||
| if (i != 1) { | ||
| final QuorumPeer qp = mt[i].getQuorumPeer(); | ||
| assertNotNull(qp); | ||
| assertEquals(2, qp.getCurrentEpoch()); | ||
| assertEquals(2, qp.getAcceptedEpoch()); | ||
| assertEquals("200000001", Long.toHexString(qp.getLastLoggedZxid())); | ||
| } | ||
| } | ||
| } | ||
|
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| private MainThread[] startQuorum(final int[] clientPorts) throws IOException { | ||
| final StringBuilder sb = new StringBuilder(); | ||
| String server; | ||
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| for (int i = 0; i < SERVER_COUNT; i++) { | ||
| clientPorts[i] = PortAssignment.unique(); | ||
| server = "server." + i + "=127.0.0.1:" + PortAssignment.unique() + ":" + PortAssignment.unique() | ||
| + ":participant;127.0.0.1:" + clientPorts[i]; | ||
| sb.append(server); | ||
| sb.append("\n"); | ||
| } | ||
|
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| final MainThread[] mt = new MainThread[SERVER_COUNT]; | ||
|
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| // start all the servers | ||
| for (int i = 0; i < SERVER_COUNT; i++) { | ||
| mt[i] = new MainThread(i, clientPorts[i], sb.toString(), false); | ||
| mt[i].start(); | ||
| } | ||
|
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| // ensure all servers started | ||
| for (int i = 0; i < SERVER_COUNT; i++) { | ||
| assertTrue( | ||
| ClientBase.waitForServerUp("127.0.0.1:" + clientPorts[i], CONNECTION_TIMEOUT), | ||
| "waiting for server " + i + " being up"); | ||
| } | ||
| return mt; | ||
| } | ||
|
|
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| private void createZKClient(final int idx) throws Exception { | ||
| zkClients[idx] = null; | ||
| final ClientBase.CountdownWatcher watch = new ClientBase.CountdownWatcher(); | ||
| zkClients[idx] = new ZooKeeper("127.0.0.1:" + clientPorts[idx], ClientBase.CONNECTION_TIMEOUT, watch); | ||
| watch.waitForConnected(ClientBase.CONNECTION_TIMEOUT); | ||
| } | ||
|
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| private String createNode(final ZooKeeper zk, final String path) throws Exception { | ||
| final String fullPath = zk.create(path, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); | ||
| assertNotNull(zk.exists(path, false)); | ||
| return fullPath; | ||
| } | ||
|
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| private static class MockTestQPMain extends TestQPMain { | ||
| @Override | ||
| protected QuorumPeer getQuorumPeer() throws SaslException { | ||
| return new TestQuorumPeer(); | ||
| } | ||
| } | ||
|
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| private static class TestQuorumPeer extends QuorumPeer { | ||
| public TestQuorumPeer() throws SaslException { | ||
| } | ||
|
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| @Override | ||
| protected Follower makeFollower(FileTxnSnapLog logFactory) throws IOException { | ||
| final FollowerZooKeeperServer followerZookeeperServer = new FollowerZooKeeperServer(logFactory, this, this.getZkDb()) { | ||
| @Override | ||
| protected void setupRequestProcessors() { | ||
| RequestProcessor finalProcessor = new FinalRequestProcessor(this); | ||
| commitProcessor = new MockCommitProcessor(finalProcessor, Long.toString(getServerId()), true, getZooKeeperServerListener()); | ||
| commitProcessor.start(); | ||
|
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| firstProcessor = new FollowerRequestProcessor(this, commitProcessor); | ||
| ((FollowerRequestProcessor) firstProcessor).start(); | ||
| syncProcessor = new MockSyncRequestProcessor(this, new SendAckRequestProcessor(getFollower())); | ||
|
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| syncProcessor.start(); | ||
| } | ||
| }; | ||
| return new Follower(this, followerZookeeperServer); | ||
| } | ||
| } | ||
|
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| private static class MockSyncRequestProcessor extends SyncRequestProcessor { | ||
| public MockSyncRequestProcessor(final ZooKeeperServer zks, final RequestProcessor nextProcessor) { | ||
| super(zks, nextProcessor); | ||
| } | ||
|
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| @Override | ||
| public void processRequest(final Request request) { | ||
| LOG.info("Sync request for zxid {} is dropped", Long.toHexString(request.getHdr().getZxid())); | ||
| } | ||
| } | ||
|
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| private static class MockCommitProcessor extends CommitProcessor { | ||
| public MockCommitProcessor(final RequestProcessor nextProcessor, final String id, | ||
| final boolean matchSyncs, final ZooKeeperServerListener listener) { | ||
|
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| super(nextProcessor, id, matchSyncs, listener); | ||
| } | ||
|
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| @Override | ||
| public void commit(final Request request) { | ||
| LOG.info("Commit request for zxid {} is dropped", Long.toHexString(request.getHdr().getZxid())); | ||
| } | ||
| } | ||
|
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| private void logEpochsAndLastLoggedTxnForAllServers() throws Exception { | ||
| for (int i = 0; i < SERVER_COUNT; i++) { | ||
| final QuorumPeer qp = mt[i].getQuorumPeer(); | ||
| if (qp != null) { | ||
| LOG.info(String.format("server id=%d, acceptedEpoch=%d, currentEpoch=%d, lastLoggedTxn=%s", | ||
| qp.getMyId(), qp.getAcceptedEpoch(), | ||
| qp.getCurrentEpoch(), Long.toHexString(qp.getLastLoggedZxid()))); | ||
| } | ||
| } | ||
| } | ||
|
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| private void validateDataFromAllClients(final List<String> paths) throws Exception{ | ||
| for (int i = 0; i < SERVER_COUNT; i++) { | ||
| if (zkClients[i] == null) { | ||
| createZKClient(i); | ||
| } | ||
|
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| for (final String path : paths) { | ||
| assertNotNull(zkClients[i].exists(path, false), "znode " + path + " is missing"); | ||
| } | ||
| assertEquals(3, paths.size()); | ||
| } | ||
| } | ||
| } |
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