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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-2849) Quorum port binding needs exponential back-off retry
Date Thu, 16 Nov 2017 22:52:01 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16256098#comment-16256098

ASF GitHub Bot commented on ZOOKEEPER-2849:

Github user afine commented on a diff in the pull request:

    --- Diff: src/java/test/org/apache/zookeeper/server/quorum/ExponentialBackoffStrategyTest.java
    @@ -0,0 +1,180 @@
    + * 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.server.quorum;
    +import static org.junit.Assert.assertEquals;
    +import static org.junit.Assert.assertNotEquals;
    +import static org.junit.Assert.assertTrue;
    +import org.junit.Test;
    + * Unit tests for {@link ExponentialBackoffStrategy}.
    + */
    +public class ExponentialBackoffStrategyTest {
    --- End diff --
    This should extend ZKTestCase

> Quorum port binding needs exponential back-off retry
> ----------------------------------------------------
>                 Key: ZOOKEEPER-2849
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2849
>             Project: ZooKeeper
>          Issue Type: Improvement
>          Components: quorum
>    Affects Versions: 3.4.6, 3.5.3
>            Reporter: Brian Lininger
>            Assignee: Brian Lininger
>            Priority: Minor
> Recently we upgraded the AWS instance type we use for running out ZooKeeper nodes, and
by doing so we're intermittently hitting an issue where ZooKeeper cannot bind to the server
election port because the IP is incorrect.  This is due to name resolution in Route53 not
being in sync when ZooKeeper starts on the more powerful EC2 instances.  Currently in QuorumCnxManager.Listener,
we only attempt to bind 3 times with a 1s sleep between retries, which is not long enough.
> I'm proposing to change this to follow an exponential back-off type strategy where each
failed attempt causes a longer sleep between retry attempts.  This would allow for Zookeeper
to gracefully recover when the host is misconfigured, and subsequently corrected, without
requiring the process to be restarted while also minimizing the impact to the running instance.

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