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From "sankalp kohli (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-7822) Confusing timeout on CAS contention
Date Mon, 25 Aug 2014 23:38:58 GMT


sankalp kohli commented on CASSANDRA-7822:

I think we should add it to the timeout in the next version. Also instead of a flag, it can
be the number of contentions you got in that request. 

"That said, WriteType.CAS should pretty much means that there has been contention and user
should probably not bother with the 'replica count' in that case. "

Not always, it could mean that none of the machines responded which can happen without contention
as well. We see that many times for LOCAL_QUORUM queries under heavy load. 

> Confusing timeout on CAS contention
> -----------------------------------
>                 Key: CASSANDRA-7822
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: sankalp kohli
>            Priority: Minor
> If we have contention in CAS and we hit the cas contention timeout, we throw an exception.
In this timeout exception, we pass that 0 replicas responded. This is very confusing to someone
looking at the client logs. I think we might need to throw a separate exception for contention
or may be add a flag in the timeout exception. 
> We have seen many people confused by this so I think we should fix it. 
> This is how we throw it on contention. 
> throw new WriteTimeoutException(WriteType.CAS, consistencyForPaxos, 0, consistencyForPaxos.blockFor(;

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