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https://issues.apache.org/jira/browse/ZOOKEEPER-1515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13421325#comment-13421325
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Ian Babrou commented on ZOOKEEPER-1515:
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I tried sleep without condition and result was almost the same. I agree that it
could be without condition.
I hope that byt function of tickTime you mean configurable multiplier in
configuration file. That would be nice.
> Long reconnect timeout if leader failed.
> ----------------------------------------
>
> Key: ZOOKEEPER-1515
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1515
> Project: ZooKeeper
> Issue Type: Improvement
> Components: leaderElection, quorum, server
> Affects Versions: 3.3.5
> Environment: Gentoo linux, but every environment is affected.
> Reporter: Ian Babrou
> Labels: patch, performance
>
> In zookeeper 3.3.5 in file
> src/java/main/org/apache/zookeeper/server/quorum/Learner.java:325 you may see
> Thread.sleep(1000);
> This is always happens after leader failure or restart. Zookeeper reelects
> new leader and all followers try to connect to it. But first attempt always
> fails because of "Connection refused":
> {quote}
> 2012-07-23 18:55:48,159 - WARN [QuorumPeer:/0.0.0.0:2181:Learner@229] -
> Unexpected exception, tries=0, connecting to web329.local/192.168.1.74:2888
> java.net.ConnectException: Connection refused
> at java.net.PlainSocketImpl.socketConnect(Native Method)
> at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
> at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
> at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
> at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
> at java.net.Socket.connect(Socket.java:529)
> at
> org.apache.zookeeper.server.quorum.Learner.connectToLeader(Learner.java:221)
> at
> org.apache.zookeeper.server.quorum.Follower.followLeader(Follower.java:65)
> at
> org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:645)
> {quote}
> I propose to change this line to the next code:
> {code:title=Learner.java|borderStyle=solid}
> if (tries > 0) {
> Thread.sleep(self.tickTime);
> }
> {code}
> This way first reconnect attempt will be done immediately, other will wait
> for tick time (this is good semantic change, I suppose).
> The result of this change - leader reelection time lowered from >1500ms to
> 300-400ms with 50ms tick time. This is pretty important for our production
> environment and will not break any existing installations.
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