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From Cameron McKenzie <cammcken...@apache.org>
Subject Re: What is connectionTimeoutMs?
Date Tue, 01 Nov 2016 22:26:52 GMT
hey Benjamin,
I've just had a quick look through the code and it seems that it's used
internally by Curator when establishing connections to ZK. If a connection
is attempted (i.e. a new Zookeeper client handle is instantiated), Curator
will allow up to the defined connection timeout MS amount of time to pass
to wait for the connection to be established. If it is not established by
this point in time it throws away the Zookeeper handle and tries again.

There's actually a warning that gets generated if you attempt to configure
the connection timeout > session timeout. I'm not positive of why this is,
but I would guess that it's because in this case it would be possible for
the session to timeout while waiting for a connection to a dead ZK node?
I'm not sure how the underlying ZK handle decides how to connect to a
particular ZK instance (it's some sort of random load sharing I think), but
I have certainly seen problems when one of the hosts in the ensemble cannot
be reached.
cheers



On Wed, Nov 2, 2016 at 9:03 AM, Benjamin Jaton <benjamin.jaton@gmail.com>
wrote:

> Hello,
>
> Is there a documentation somewhere about what connectionTimeoutMs
> represents?
>
> The only thing I could find was:
> https://curator.apache.org/apidocs/org/apache/curator/framework/
> CuratorFrameworkFactory.html
>
> Which simply states:
>     connectionTimeoutMs - connection timeout
>
> I am asking because it seems like we HAVE to use a connectionTimeoutMs
> that is greater than the sessionTimeout, otherwise we may run into
> CURATOR-355 (also if that is the case, it would be nice to just enforce it
> or at least log and warn/error).
>
> Thanks,
> Benjamin
>

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