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From "Sergio Bossa (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-9318) Bound the number of in-flight requests at the coordinator
Date Fri, 23 Oct 2015 18:40:28 GMT


Sergio Bossa commented on CASSANDRA-9318:

bq. The whole point of this ticket is to avoid the complexity of intra-node backpressure,
and instead basing coordinator -> client backpressure on the coordinator's local knowledge.

Just to be clear, my proposal _does_ keep the back-pressure decision local to the coordinator,
that is, there's no communication between nodes in such regard (which I agree would be a much
different matter). The difference in my proposal is that we deal with back-pressure on a per-replica
basis and in a fine grained way, rather than with coarse grained global memory limits which
would end up flooding replicas before being triggered.

> Bound the number of in-flight requests at the coordinator
> ---------------------------------------------------------
>                 Key: CASSANDRA-9318
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Ariel Weisberg
>            Assignee: Jacek Lewandowski
>             Fix For: 2.1.x, 2.2.x
> It's possible to somewhat bound the amount of load accepted into the cluster by bounding
the number of in-flight requests and request bytes.
> An implementation might do something like track the number of outstanding bytes and requests
and if it reaches a high watermark disable read on client connections until it goes back below
some low watermark.
> Need to make sure that disabling read on the client connection won't introduce other

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