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https://issues.apache.org/jira/browse/STORM-841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14566965#comment-14566965
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ASF GitHub Bot commented on STORM-841:
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GitHub user HeartSaVioR opened a pull request:
https://github.com/apache/storm/pull/569
STORM-841 Correct doc that OutputCollector is not thread-safe
* Concepts.md: Correct document
* Troubleshooting.md: Add stack trace for other NPE case caused by same
issue
** Related to STORM-770
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/HeartSaVioR/storm STORM-841
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/storm/pull/569.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 #569
----
commit a6c46aec300001095fee6396ce8ffd4a0fd5783a
Author: Jungtaek Lim <kabh...@gmail.com>
Date: 2015-06-01T06:03:31Z
STORM-841 Correct doc that OutputCollector is not thread-safe
----
> Thread-safeness of OutputCollector has documented contrary to two official
> doc.
> -------------------------------------------------------------------------------
>
> Key: STORM-841
> URL: https://issues.apache.org/jira/browse/STORM-841
> Project: Apache Storm
> Issue Type: Documentation
> Reporter: Jungtaek Lim
> Priority: Critical
>
> There're some issues with documentation.
> http://storm.apache.org/documentation/Concepts.html says
> {quote}
> Its perfectly fine to launch new threads in bolts that do processing
> asynchronously. OutputCollector is thread-safe and can be called at any time.
> {quote}
> and http://storm.apache.org/documentation/Troubleshooting.html says
> {quote}
> This is caused by having multiple threads issue methods on the
> OutputCollector. All emits, acks, and fails must happen on the same thread.
> One subtle way this can happen is if you make a IBasicBolt that emits on a
> separate thread. IBasicBolt's automatically ack after execute is called, so
> this would cause multiple threads to use the OutputCollector leading to this
> exception. When using a basic bolt, all emits must happen in the same thread
> that runs execute.
> {quote}
> It is a contradiction, and at least for now OutputCollector is not
> thread-safe.
> https://www.mail-archive.com/dev@storm.incubator.apache.org/msg00939.html
> Since newbie of Storm users may think Concepts page as "should read and keep
> it mind", it is some kind of critical that that such important documentation
> page has wrong content.
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