[
https://issues.apache.org/jira/browse/ZOOKEEPER-2959?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16434910#comment-16434910
]
ASF GitHub Bot commented on ZOOKEEPER-2959:
-------------------------------------------
Github user anmolnar commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/500#discussion_r180793047
--- Diff: src/java/test/org/apache/zookeeper/server/quorum/Zab1_0Test.java
---
@@ -245,6 +245,180 @@ public void testLastAcceptedEpoch() throws Exception {
recursiveDelete(tmpDir);
}
}
+
+ @Test
+ public void testGetEpochToProposeWithObserver() throws Exception {
+ File tmpDir = File.createTempFile("test", "dir", testData);
+ tmpDir.delete();
+ tmpDir.mkdir();
+ Leader leader = null;
+ try {
+ QuorumPeer peer = createQuorumPeer(tmpDir);
+ long participantId = 1;
+ long observerId = peer.quorumPeers.size();
+ peer.quorumPeers.put(observerId, new QuorumServer(observerId,
"0.0.0.0", 33225,
--- End diff --
I think to be consistent with `createQuorumPeer()` method this should be
something like:
```
peers.put(observerId, new QuorumServer(observerId, new
InetSocketAddress("127.0.0.1", PortAssignment.unique()),
new InetSocketAddress("127.0.0.1", PortAssignment.unique()),
new InetSocketAddress("127.0.0.1", PortAssignment.unique()),
QuorumPeer.LearnerType.OBSERVER));
```
> ignore accepted epoch and LEADERINFO ack from observers when a newly elected
> leader computes new epoch
> ------------------------------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-2959
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2959
> Project: ZooKeeper
> Issue Type: Bug
> Affects Versions: 3.4.10, 3.5.3
> Reporter: xiangyq000
> Assignee: Bogdan Kanivets
> Priority: Blocker
>
> Once the ZooKeeper cluster finishes the election for new leader, all learners
> report their accepted epoch to the leader for the computation of new cluster
> epoch.
> org.apache.zookeeper.server.quorum.Leader#getEpochToPropose
> {code:java}
> private final HashSet<Long> connectingFollowers = new HashSet<Long>();
> public long getEpochToPropose(long sid, long lastAcceptedEpoch) throws
> InterruptedException, IOException {
> synchronized(connectingFollowers) {
> if (!waitingForNewEpoch) {
> return epoch;
> }
> if (lastAcceptedEpoch >= epoch) {
> epoch = lastAcceptedEpoch+1;
> }
> connectingFollowers.add(sid);
> QuorumVerifier verifier = self.getQuorumVerifier();
> if (connectingFollowers.contains(self.getId()) &&
>
> verifier.containsQuorum(connectingFollowers)) {
> waitingForNewEpoch = false;
> self.setAcceptedEpoch(epoch);
> connectingFollowers.notifyAll();
> } else {
> long start = Time.currentElapsedTime();
> long cur = start;
> long end = start + self.getInitLimit()*self.getTickTime();
> while(waitingForNewEpoch && cur < end) {
> connectingFollowers.wait(end - cur);
> cur = Time.currentElapsedTime();
> }
> if (waitingForNewEpoch) {
> throw new InterruptedException("Timeout while waiting for
> epoch from quorum");
> }
> }
> return epoch;
> }
> }
> {code}
> The computation will get an outcome once :
> # The leader has call method "getEpochToPropose"
> # The number of all reporters is greater than half of participants.
> The problem is, an observer server will also send its accepted epoch to the
> leader, while this procedure treat observers as participants.
> Supposed that the cluster consists of 1 leader, 2 followers and 1 observer,
> and now the leader and the observer have reported their accepted epochs while
> neither of the followers has. Thus, the connectingFollowers set consists of
> two elements, resulting in a size of 2, which is greater than half quorum,
> namely, 2. Then QuorumVerifier#containsQuorum will return true, because it
> does not check whether the elements of the parameter are participants.
> The same flaw exists in
> org.apache.zookeeper.server.quorum.Leader#waitForEpochAck
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