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Date: Thu, 8 Jun 2017 22:12:18 +0000 (UTC)
From: "ASF GitHub Bot (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (ZOOKEEPER-1748) TCP keepalive for leader
 election connections
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archived-at: Thu, 08 Jun 2017 22:12:22 -0000


    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1748?page=3Dcom.atlas=
sian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D=
16043532#comment-16043532 ]=20

ASF GitHub Bot commented on ZOOKEEPER-1748:
-------------------------------------------

Github user bensherman commented on the issue:

    https://github.com/apache/zookeeper/pull/276
 =20
    Version number fixed!


> TCP keepalive for leader election connections
> ---------------------------------------------
>
>                 Key: ZOOKEEPER-1748
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1748
>             Project: ZooKeeper
>          Issue Type: Improvement
>          Components: leaderElection
>    Affects Versions: 3.4.5, 3.5.0
>         Environment: Linux, Java 1.7
>            Reporter: Antal Sasv=C3=A1ri
>            Assignee: Daniel Peon
>            Priority: Minor
>             Fix For: 3.4.11
>
>         Attachments: Zookeeper-1748-add_tcp_keepalive.patch
>
>
> In our system we encountered the following problem:
> If the system is stable, and there is no leader election, the leader elec=
tion port connections are open for very long time without any packets being=
 sent on them.
> Some network elements silently drop the established TCP connection after =
a timeout if there are no packets being sent on it. In this case the ZK ser=
vers will not notice the connection loss. This causes additional delay late=
r when the next leader election is started, as the TCP connections are not =
alive any more.
> We would like to be able to enable TCP keepalive on the leader election s=
ockets in order to prevent the connection timeout in some network elements =
due to connection inactivity.
> This could be controlled by adding a new config parameter called tcpKeepA=
live in the ZooKeeper configuration file. It would be only applicable in ca=
se of algorithm 3 (TCP based fast leader election), having the default valu=
e false.
> If tcpKeepAlive is set to true, the TCP keepalive flag should be enabled =
for the leader election sockets in QuorumCnxManager.setSockOpts() by callin=
g sock.setKeepAlive(true).
> We have tested this change successfully in our environment.
> Please comment whether you see any problem with this. If not, I am going =
to submit a patch.
> I've been told that e.g. Apache ActiveMQ also has a config option for sim=
ilar purpose called transport.keepalive.


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