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https://issues.apache.org/jira/browse/HADOOP-4521?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12642619#action_12642619
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Amar Kamat commented on HADOOP-4521:
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One way I can think is to have the listeners add themselves to a
{{JobListenerManager}} which will be implemented by the {{JobTracker}}. The
{{JobListenerManager}} interface, for now, will implement the following
interfaces
- addJobInProgressListener(JobInProgressListener)
- removeJobInProgressListener(JobInProgressListener)
- update(JobChangeEvent)
For example a listener might init the job, generate an event and then inform
the {{JobListenerManager}} about it.
Also the {{JobInProgressListener}} interface should add itself to the
{{JobListenerManager}} rather than some third party adding it. This can be done
by adding a {{addJobListenerManager(JobListenerManager)}} interface to
{{JobInProgressListener}} or extend the listener's constructor to accept a
{{JobListenerManager}}.
Internally the listener should maintain the reference to the
{{JobListenerManager}} and should change/update a job only via
{{JobListenerManager.update()}}.
JobListenerManager should take the responsibility of updating other listeners.
> A JobInProgressLIstener can change a job without informing other listeners
> --------------------------------------------------------------------------
>
> Key: HADOOP-4521
> URL: https://issues.apache.org/jira/browse/HADOOP-4521
> Project: Hadoop Core
> Issue Type: Improvement
> Components: mapred
> Reporter: Amar Kamat
>
> As of now the {{JobInProgressListener}} adds itself to the {{JobTracker}} and
> gets updated/informed. Some of there {{JobInProgressListener}}'s control
> these changes/events (e.g. {{EagerTaskInitializer}}). The issue with this
> model is that a listener can change the job without informing other
> listeners.
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