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https://issues.apache.org/jira/browse/STORM-886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14717230#comment-14717230
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ASF GitHub Bot commented on STORM-886:
--------------------------------------
Github user knusbaum commented on a diff in the pull request:
https://github.com/apache/storm/pull/700#discussion_r38128803
--- Diff: storm-core/src/clj/backtype/storm/daemon/worker.clj ---
@@ -137,9 +159,14 @@
(.add remote (TaskMessage. task (.serialize
serializer tuple)))
(log-warn "Can't transfer tuple - task value is
nil. tuple type: " (pr-str (type tuple)) " and information: " (pr-str tuple)))
))))
- (local-transfer local)
- (disruptor/publish transfer-queue remoteMap)
- ))]
+ ;; each executor itself will do the self setting for the
worker's backpressure tag
+ ;; however, when the backpressure is set, the worker still
need to check whether all the executors' flag has cleared to unset worker's
backpressure
+ (if (and ((:storm-conf worker) TOPOLOGY-BACKPRESSURE-ENABLE)
(> (.population transfer-queue) high-watermark))
--- End diff --
Here too.
> 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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