Jared Cantwell commented on ZOOKEEPER-906:

I like this idea-- we ran into an issue with this recently too.  I was looking 
at your patch and don't understand how the last_connect_index works.  It seems 
like its intention is to store the last successful connection that was 
established.  However, it seems to only be assigned a value before a connection 
is established.  Based on what I can tell:

1. it will get set to the very fist connect_index
2. connections will loop around, but it won't get reset since 
last_connect_index != -1
3. once reconnections make it around to the beginning, it will get reset to -1 
4. then the very next connect_index will get assigned to that same connect_index

Please let me know what I am missing.

> Improve C client connection reliability by making it sleep between reconnect 
> attempts as in Java Client
> -------------------------------------------------------------------------------------------------------
>                 Key: ZOOKEEPER-906
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-906
>             Project: Zookeeper
>          Issue Type: Improvement
>          Components: c client
>    Affects Versions: 3.3.1
>            Reporter: Radu Marin
>            Assignee: Radu Marin
>             Fix For: 3.4.0
>         Attachments: ZOOKEEPER.patch
>   Original Estimate: 24h
>  Remaining Estimate: 24h
> Currently, when a C client get disconnected, it retries a couple of hosts 
> (not all) with no delay between attempts and then if it doesn't succeed it 
> sleeps for 1/3 session expiration timeout period before trying again.
> In the worst case the disconnect event can occur after 2/3 of session 
> expiration timeout has past, and sleeping for even more 1/3 session timeout 
> will cause a session loss in most of the times.
> A better approach is to check all hosts but with random delay between 
> reconnect attempts. Also the delay must be independent of session timeout so 
> if we increase the session timeout we also increase the number of available 
> attempts.
> This improvement covers the case when the C client experiences network 
> problems for a short period of time and is not able to reach any zookeeper 
> hosts.
> Java client already uses this logic and works very good.

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