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ASF GitHub Bot commented on STORM-886: -------------------------------------- Github user asfgit closed the pull request at: https://github.com/apache/storm/pull/700 > 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. -- This message was sent by Atlassian JIRA (v6.3.4#6332)