[
https://issues.apache.org/jira/browse/STORM-746?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14392735#comment-14392735
]
ASF GitHub Bot commented on STORM-746:
--------------------------------------
GitHub user d2r opened a pull request:
https://github.com/apache/storm/pull/499
[STORM-746] Skip ack init when there are no output tasks
See [STORM-746](https://issues.apache.org/jira/browse/STORM-746) for the
description.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/d2r/storm storm-746-ack-init-shortcut
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/storm/pull/499.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #499
----
commit 6602c4becb7f22a14faab032872e51f70864530a
Author: Derek Dagit <[email protected]>
Date: 2015-04-02T13:55:03Z
Skip ack init when there are no output tasks
----
> Disable Spout Ack Init when there is no output task
> ---------------------------------------------------
>
> Key: STORM-746
> URL: https://issues.apache.org/jira/browse/STORM-746
> Project: Apache Storm
> Issue Type: Improvement
> Affects Versions: 0.9.2-incubating
> Reporter: Derek Dagit
> Assignee: Derek Dagit
> Priority: Minor
>
> Suppose a user cannot easily modify the spout in the topology.
> The user has temporarily disabled transferring of tuples from a spout, for
> debugging.
> In this case, when acking is used, each time the spout emits, it sends a
> tuple to the acker bolt. The bolt executes on this tuple by initializing the
> bit-field used for tracking when the tuple "tree" has completed processing
> (XOR-ing the new field with 0), then checking whether processing is complete
> (by comparing the field to 0), and finally sending an ack in reply to the
> spout.
> Normally, this is not a problem beyond the overhead, but on at least one
> occasion in the course of debugging topology performance, the acker bolt's
> host was so overloaded that it actually could not send the reply ack back to
> the spout before the spout timed it out. This resulted in a lot of Fails
> reported for tuples that were not supposed to go anywhere in the first place,
> and an unnecessary count against the max.spout.pending that evidently also
> makes it harder to debug.
> This was very confusing to the user.
> I propose that we short-cut the ack init in the case when the spout does not
> emit to any downstream tasks.
> I do have some misgivings already about making this change, as a spout
> emitting nowhere could be considered outside the set of normal use cases for
> Storm. That said, I will not be unhappy if someone gives a -1.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
