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https://issues.apache.org/jira/browse/ZOOKEEPER-2988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16384209#comment-16384209
]
ASF GitHub Bot commented on ZOOKEEPER-2988:
-------------------------------------------
Github user afine commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/476#discussion_r171972029
--- Diff:
src/java/test/org/apache/zookeeper/server/quorum/QuorumPeerMainTest.java ---
@@ -1012,4 +1012,113 @@ public void testFailedTxnAsPartOfQuorumLoss()
throws Exception {
Assert.assertNull("server " + i + " should not have /zk" +
leader, servers.zk[i].exists("/zk" + leader, false));
}
}
+
+ /**
+ * Verify that a node without the leader in its view will not attempt
to connect to the leader.
+ */
+ @Test
+ public void testLeaderOutOfView() throws Exception {
+ ClientBase.setupTestEnv();
+
+ Layout layout = new PatternLayout("%d{ISO8601} [,yid:%X{myid}] -
%5p [%t:%C{1}@%L] - %m%n");
+ ByteArrayOutputStream os = new ByteArrayOutputStream();
+ WriterAppender appender = new WriterAppender(layout, os);
+ appender.setThreshold(Level.DEBUG);
+ Logger qlogger =
Logger.getLogger("org.apache.zookeeper.server.quorum");
+ qlogger.addAppender(appender);
+
+ try {
+ final int CLIENT_PORT_QP1 = PortAssignment.unique();
+ final int CLIENT_PORT_QP2 = PortAssignment.unique();
+ final int CLIENT_PORT_QP3 = PortAssignment.unique();
+
+ String quorumCfgIncomplete = getUniquePortCfgForId(1) + "\n" +
getUniquePortCfgForId(2);
+ String quorumCfgComplete = quorumCfgIncomplete + "\n" +
getUniquePortCfgForId(3);
+
+ // Node 1 is started without the leader (3) in its config view
+ MainThread q1 = new MainThread(1, CLIENT_PORT_QP1,
quorumCfgIncomplete);
+ MainThread q2 = new MainThread(2, CLIENT_PORT_QP2,
quorumCfgComplete);
+ MainThread q3 = new MainThread(3, CLIENT_PORT_QP3,
quorumCfgComplete);
+
+ // Node 1 must be started first, before quorum is formed, to
trigger the attempted invalid connection to 3
+ q1.start();
+ QuorumPeer quorumPeer1 = waitForQuorumPeer(q1,
CONNECTION_TIMEOUT);
+ Assert.assertTrue(quorumPeer1.getPeerState() ==
QuorumPeer.ServerState.LOOKING);
+
+ // Node 3 started second to avoid 1 and 2 forming a quorum
before 3 starts up
+ q3.start();
+ QuorumPeer quorumPeer3 = waitForQuorumPeer(q3,
CONNECTION_TIMEOUT);
+ Assert.assertTrue(quorumPeer3.getPeerState() ==
QuorumPeer.ServerState.LOOKING);
+
+ // Node 2 started last, kicks off leader election
+ q2.start();
+
+ // Nodes 2 and 3 now form quorum and fully start. 1 attempts
to vote for 3, fails, returns to LOOKING state
+ Assert.assertTrue("waiting for server 2 to start",
+ ClientBase.waitForServerUp("127.0.0.1:" +
CLIENT_PORT_QP2, CONNECTION_TIMEOUT));
+ Assert.assertTrue("waiting for server 3 to start",
+ ClientBase.waitForServerUp("127.0.0.1:" +
CLIENT_PORT_QP3, CONNECTION_TIMEOUT));
+
+ Assert.assertTrue(q1.getQuorumPeer().getPeerState() ==
QuorumPeer.ServerState.LOOKING);
+ Assert.assertTrue(q2.getQuorumPeer().getPeerState() ==
QuorumPeer.ServerState.FOLLOWING);
+ Assert.assertTrue(q3.getQuorumPeer().getPeerState() ==
QuorumPeer.ServerState.LEADING);
+
+ q1.shutdown();
+ q2.shutdown();
+ q3.shutdown();
+
+ Assert.assertTrue("waiting for server 1 down",
+ ClientBase.waitForServerDown("127.0.0.1:" +
CLIENT_PORT_QP1,
+ ClientBase.CONNECTION_TIMEOUT));
+ Assert.assertTrue("waiting for server 2 down",
+ ClientBase.waitForServerDown("127.0.0.1:" +
CLIENT_PORT_QP2,
+ ClientBase.CONNECTION_TIMEOUT));
+ Assert.assertTrue("waiting for server 3 down",
+ ClientBase.waitForServerDown("127.0.0.1:" +
CLIENT_PORT_QP3,
+ ClientBase.CONNECTION_TIMEOUT));
+
+ } finally {
+ qlogger.removeAppender(appender);
+ }
+
+ // Verify that Node 1 never threw an exception
+ LineNumberReader r = new LineNumberReader(new
StringReader(os.toString()));
+ String line;
+ boolean found = false;
+ Pattern p = Pattern.compile(".*java.lang.NullPointerException.*");
+ while ((line = r.readLine()) != null) {
+ found = p.matcher(line).matches();
+ if (found) {
+ break;
+ }
+ }
+
+ Assert.assertFalse("Node should not attempt connection to out of
view leader", found);
+ }
+
+ private String getUniquePortCfgForId(int id) {
+ return String.format("server.%d=127.0.0.1:%d:%d", id,
PortAssignment.unique(), PortAssignment.unique());
+ }
+
+ private QuorumPeer waitForQuorumPeer(MainThread mainThread, int
timeout) {
+ long start = Time.currentElapsedTime();
+ while (true) {
+ QuorumPeer quorumPeer = mainThread.getQuorumPeer();
+ if (quorumPeer != null) {
+ return quorumPeer;
+ }
+
+ if (Time.currentElapsedTime() > start + timeout) {
+ LOG.error("Timed out while waiting for QuorumPeer");
+ break;
+ }
+
+ try {
+ Thread.sleep(250);
+ } catch (InterruptedException e) {
+ // ignore
+ }
+ }
+ throw new NullPointerException();
--- End diff --
Can we use a better exception?
> NPE triggered if server receives a vote for a server id not in their voting
> view
> --------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-2988
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2988
> Project: ZooKeeper
> Issue Type: Bug
> Components: leaderElection
> Affects Versions: 3.5.3, 3.4.11
> Reporter: Brian Nixon
> Priority: Minor
>
> We've observed the following behavior in elections when a node is lagging
> behind the quorum in its view of the ensemble topology.
> - Node A is operating with node B in its voting view, but without view of
> node C.
> - B votes for C.
> - A then switches its vote to C, but throws a NPE when attempting to connect.
> This causes the QuorumPeer to spin up a Follower only to immediately have it
> shutdown by the exception.
> Ideally, A would not advertise a vote for a server that it will not follow.
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