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https://issues.apache.org/jira/browse/STORM-329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14318317#comment-14318317
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ASF GitHub Bot commented on STORM-329:
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Github user clockfly commented on the pull request:
https://github.com/apache/storm/pull/429#issuecomment-74084548
+1
On Thu, Feb 12, 2015 at 6:44 PM, Michael G. Noll <[email protected]>
wrote:
> Thanks for your feedback, Nathan.
>
> As far as I understand this patch does not enable backpressure. But:
> because there is no backpressure (yet) that we can rely on, this patch
will
> improve at least the situation during the startup phase of a topology to
> prevent that a) an unacked topo will not lose messages during the startup,
> and b) we do not need to unnecessarily replay messages in case of acked
> topos during their startup. This is achieved by checking that all worker
> connections are ready before the topology starts processing data.
>
> So backpressure is still an open feature. Backpressure was IIRC mentioned
> in the initial PR because there was a deficiency (dating back to a ZMQ
> related TODO) that caused problems related to this PR/Storm tickets (327,
> 404, and one more). However, this patch does make the best of the current
> situation even in the absence of backpressure. But first and foremost this
> patch fixes a (critical) cascading failure that can bring Storm clusters
to
> a halt.
>
> Please correct me if I'm mistaken in my summary.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/apache/storm/pull/429#issuecomment-74050954>.
>
> Add Option to Config Message handling strategy when connection timeout
> ----------------------------------------------------------------------
>
> Key: STORM-329
> URL: https://issues.apache.org/jira/browse/STORM-329
> Project: Apache Storm
> Issue Type: Improvement
> Affects Versions: 0.9.2-incubating
> Reporter: Sean Zhong
> Priority: Minor
> Labels: Netty
> Attachments: storm-329.patch, worker-kill-recover3.jpg
>
>
> This is to address a [concern brought
> up|https://github.com/apache/incubator-storm/pull/103#issuecomment-43632986]
> during the work at STORM-297:
> {quote}
> [~revans2] wrote: Your logic makes since to me on why these calls are
> blocking. My biggest concern around the blocking is in the case of a worker
> crashing. If a single worker crashes this can block the entire topology from
> executing until that worker comes back up. In some cases I can see that being
> something that you would want. In other cases I can see speed being the
> primary concern and some users would like to get partial data fast, rather
> then accurate data later.
> Could we make it configurable on a follow up JIRA where we can have a max
> limit to the buffering that is allowed, before we block, or throw data away
> (which is what zeromq does)?
> {quote}
> If some worker crash suddenly, how to handle the message which was supposed
> to be delivered to the worker?
> 1. Should we buffer all message infinitely?
> 2. Should we block the message sending until the connection is resumed?
> 3. Should we config a buffer limit, try to buffer the message first, if the
> limit is met, then block?
> 4. Should we neither block, nor buffer too much, but choose to drop the
> messages, and use the built-in storm failover mechanism?
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