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Date: Tue, 17 Nov 2015 10:10:24 -0800
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 <CAMUR=Wi=JXdfdUt0kBHKFcCMKgT4X61wKkRp8riQTky8MRd4HA@mail.gmail.com>
Subject: Re: Transaction timeouts
From: =?UTF-8?B?UmHDumwgR3V0acOpcnJleiBTZWdhbMOpcw==?= <rgs@itevenworks.net>
To: "user@zookeeper.apache.org" <user@zookeeper.apache.org>
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Hi,

On 17 November 2015 at 05:10, Akmal Abbasov <akmal.abbasov@icloud.com>
wrote:

> Hi, I=E2=80=99m seeing a lot of `Closing connection to peer due to transa=
ction
> timeout` messages in zk logs, in all zk servers.
> Is this transaction timeout configured through syncLimit in zk config fil=
e.
>

That message comes from LearnerHandler#ping() [0], and the frequency of
pings from the leader to learners
is twice a tick [1]. So if your tickTime is 2000ms (the default), you are
pinging the learners every second. You could
adjust the tickTime and see if it gets better. But I suspect something else
(GC-ing? noisy network?) is going on, given that it
shouldn't be that hard for the leader and learners to keep up with 1 ping
every sec.

You can check ZAB messages (i.e.: pings, acks, commits, proposals, etc.)
between the leader and learners using zktraffic's
zk-dump [2].


> Also does zk server need to be restarted in order to update this config?
>

yes.


-rgs

[0]
https://github.com/apache/zookeeper/blob/trunk/src/java/main/org/apache/zoo=
keeper/server/quorum/LearnerHandler.java#L923
[1]
https://github.com/apache/zookeeper/blob/trunk/src/java/main/org/apache/zoo=
keeper/server/quorum/Leader.java#L549
[2] https://github.com/twitter/zktraffic

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