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https://issues.apache.org/jira/browse/STORM-886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14715339#comment-14715339
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ASF GitHub Bot commented on STORM-886:
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Github user revans2 commented on a diff in the pull request:
https://github.com/apache/storm/pull/700#discussion_r38021285
--- Diff: conf/defaults.yaml ---
@@ -140,6 +140,14 @@ task.heartbeat.frequency.secs: 3
task.refresh.poll.secs: 10
task.credentials.poll.secs: 30
+# now should be null by default
+topology.backpressure.enable: true
+backpressure.worker.high.watermark: 0.9
+backpressure.worker.low.watermark: 0.4
+backpressure.executor.high.watermark: 0.9
+backpressure.executor.low.watermark: 0.4
+backpressure.spout.suspend.time.ms: 100
--- End diff --
This seems way too high. It is not that expensive to poll at a 1ms
interval in the spout waiting for back-pressure to be turned off.
> 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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