[
https://issues.apache.org/jira/browse/STORM-658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14598635#comment-14598635
]
Derek Dagit commented on STORM-658:
-----------------------------------
This Issue raises a valid point that Storm's behavior with a null value for
{{topology.acker.executors}} might seem surprising. Whether or not the Acker
Executors will be used depends on the code. If the topology components intend
to make use of Acking, then it would be good for the common case to be handled.
One Acker Executor per Worker seems like a good default here, so I am not too
interested in changing it. I could be convinced otherwise.
What we might want to do instead is change the documentation—both the Markdown
and the JavaDoc—to explicitly describe what the default behavior is. We would
want to update the description in Config.java and update our document titled
"Guaranteeing Message Processing." (Incidentally, the latter document already
describes how to disable launching of the Acker Executors if you know that you
do not want acking, which is to use {{0}}.)
We might also want to either update the example Topologies to actually make use
of acking or else update them not to launch the Ackers at all so as to avoid
possibly confusing users.
Another thought is that perhaps we should not count Executors that are devoted
to running system Tasks like the Acker on the UI Topology Summary, since we
have a button at the bottom that enables or disables inclusion of the system
stats. I looked at the UI code, and it seems we have been counting Acker
Executors in the Topology Summary for a very long time. So far we have simply
counted all the Executors in the Topology whether or not the user asked to show
System Stats.
> config topology.acker.executors default value is null and then should not
> start acker bolts
> -------------------------------------------------------------------------------------------
>
> Key: STORM-658
> URL: https://issues.apache.org/jira/browse/STORM-658
> Project: Apache Storm
> Issue Type: Bug
> Reporter: caofangkun
> Assignee: caofangkun
> Priority: Minor
> Attachments: executors num is wrong.png, is null.png
>
>
> See Code:
> https://github.com/caofangkun/apache-storm/blob/master/storm-core/src/clj/backtype/storm/daemon/common.clj#L315
> Config "topology.acker.executors" default value is null
> then acker executors will be same as "topology.workers"
> $ storm jar storm-starter-0.10.0-SNAPSHOT.jar
> storm.starter.ExclamationTopology ExclamationTopology
> Executors show up as 18 executors = 10(word) + 3(exclaim1) + 2(exclaim2) +
> 3(acker bolt)
> But the 3 acker bolt executors will not be used.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
