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https://issues.apache.org/jira/browse/STORM-886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14717701#comment-14717701
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ASF GitHub Bot commented on STORM-886:
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Github user zhuoliu commented on the pull request:
https://github.com/apache/storm/pull/700#issuecomment-135577332
Addressed comments:
a. Removed the config of suspend time, reuse the empty emit and put the
judgement together with max.spout.pending
b. Separate functions for credentials and throttle checks in
schedule-recurring thread
c. Update worker flag to ZK only when it has changed (for reducing ZK load)
d. Other comments like type hint and And.
To continue work on the other three comments:
a. Add metrics for executor's suspending times for throttle-on, inactive,
spout.spending etc.
b. Concern on the possible corner cases since I put the backpressure checks
in tuple-action-fn.
c. Unit tests.
> Automatic Back Pressure
> -----------------------
>
> Key: STORM-886
> URL: https://issues.apache.org/jira/browse/STORM-886
> Project: Apache Storm
> Issue Type: Improvement
> Reporter: Robert Joseph Evans
> Assignee: Zhuo Liu
> Attachments: an simple example for backpressure.png, backpressure.png
>
>
> This new feature is aimed for automatic flow control through the topology DAG
> since different components may have unmatched tuple processing speed.
> Currently, the tuples may get dropped if the downstream components can not
> process as quickly, thereby causing a waste of network bandwidth and
> processing capability. In addition, it is difficult to tune the
> max.spout.pending parameter for best backpressure performance. Therefore, an
> automatic back pressure scheme is highly desirable.
> Heron proposed a form of back pressure that does not rely on acking or max
> spout pending. Instead spouts throttle not only when max.spout.pending is
> hit, but also if any bolt has gone over a high water mark in their input
> queue, and has not yet gone below a low water mark again. There is a lot of
> room for potential improvement here around control theory and having spouts
> only respond to downstream bolts backing up, but a simple bang-bang
> controller like this is a great start.
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