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https://issues.apache.org/jira/browse/ZOOKEEPER-1748?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14565272#comment-14565272
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Raul Gutierrez Segales commented on ZOOKEEPER-1748:
---------------------------------------------------
Sorry for the slowness [~gdrot]! Would you mind rebasing the patch on trunk
since it doesn't apply cleanly anymore?
Also, a few nits:
In:
{code}
private void setSockOpts(Socket sock) throws SocketException {
sock.setTcpNoDelay(true);
+ LOG.info("Settings keepAlive to " + self.tcpKeepAlive + " on socket");
+ sock.setKeepAlive(self.tcpKeepAlive);
{code}
you can probably drop that LOG.info call, since it's logged from
QuorumPeer#setTcpKeepAlive already. And for the log call in
QuorumPeer#setTcpKeepAlive it would be nice to use extrapolation instead of
string concatenation, i.e.:
{code}
+ public void setTcpKeepAlive(boolean tcpKeepAlive) {
+ LOG.info("tcpKeepAlive set to {}", tcpKeepAlive);
+ this.tcpKeepAlive = tcpKeepAlive;
+ }
{code}
Other than that, +1 lgtm. Btw, we are using this patch internally so I can
attest it works great too.
Also, it would be nice to document this new configuration property, i.e.:
{code}
--- a/docs/zookeeperAdmin.html
+++ b/docs/zookeeperAdmin.html
@@ -1358,6 +1358,14 @@ server.3=zoo3:2888:3888</pre>
</div>
</div>
</dd>
+<term>tcpKeepAliveEnabled</term>
+</dt>
+<dd>
+<p>(No Java system property)</p>
+<p><Strong>New in 3.5.0:</strong> Sets the keepAlive flag on the sockets used
by quorum
+ members to perform elections. Defaults to <strong>false</strong>.
+</p>
+</dd>
{code}
Thanks!
> 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 Sasvári
> Assignee: Daniel Peon
> Priority: Minor
> Fix For: 3.5.2, 3.6.0
>
> 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 election
> 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 servers
> will not notice the connection loss. This causes additional delay later 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
> sockets 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 tcpKeepAlive
> in the ZooKeeper configuration file. It would be only applicable in case of
> algorithm 3 (TCP based fast leader election), having the default value false.
> If tcpKeepAlive is set to true, the TCP keepalive flag should be enabled for
> the leader election sockets in QuorumCnxManager.setSockOpts() by calling
> 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 similar
> purpose called transport.keepalive.
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