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https://issues.apache.org/jira/browse/FLINK-10052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16884567#comment-16884567
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lamber-ken commented on FLINK-10052:
------------------------------------
Hi, all.
BTW, if we upgrade curator dependency to 4.x, there's a problem that
curator-4.x detect the version of zookeeper by test
whether +org.apache.zookeeper.admin.ZooKeeperAdmin+ is in classpath or not. But
flink-runtime module will shade +org.apache.zookeeper+ to
+org.apache.flink.shaded.zookeeper.org.apache.zookeeper.+ So it will not fix
this issue by upgrading curator's version.
Here is [Curator
Compatibility|https://github.com/apache/curator/blob/master/curator-client/src/main/java/org/apache/curator/utils/Compatibility.java].
> Tolerate temporarily suspended ZooKeeper connections
> ----------------------------------------------------
>
> Key: FLINK-10052
> URL: https://issues.apache.org/jira/browse/FLINK-10052
> Project: Flink
> Issue Type: Improvement
> Components: Runtime / Coordination
> Affects Versions: 1.4.2, 1.5.2, 1.6.0, 1.8.1
> Reporter: Till Rohrmann
> Assignee: Dominik Wosiński
> Priority: Major
>
> This issue results from FLINK-10011 which uncovered a problem with Flink's HA
> recovery and proposed the following solution to harden Flink:
> The {{ZooKeeperLeaderElectionService}} uses the {{LeaderLatch}} Curator
> recipe for leader election. The leader latch revokes leadership in case of a
> suspended ZooKeeper connection. This can be premature in case that the system
> can reconnect to ZooKeeper before its session expires. The effect of the lost
> leadership is that all jobs will be canceled and directly restarted after
> regaining the leadership.
> Instead of directly revoking the leadership upon a SUSPENDED ZooKeeper
> connection, it would be better to wait until the ZooKeeper connection is
> LOST. That way we would allow the system to reconnect and not lose the
> leadership. This could be achievable by using Curator's {{LeaderSelector}}
> instead of the {{LeaderLatch}}.
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