[jira] Commented: (HADOOP-2086) ability to add dependencies to a job after construction

[Runping Qi (JIRA)]

    [ 
https://issues.apache.org/jira/browse/HADOOP-2086?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12537706
 ] 

Runping Qi commented on HADOOP-2086:
------------------------------------


I like 1).

Yes, there is a possibility of race condition when the JobControl may be also 
checking the state of the job. 
One solution is to make them synchronized:

{code}
synchronized public boolean addDependingJob(Job dependingJob) {
    if (this.state == Job.WAITING) { 
        //code to add depending job to list goes here 
    } else { 
        return false; 
    }
}

synchronized int checkState() {
 ...
}
{/code}

Maybe it is also a good idea to make checkState() package private since it 
should not be called externally.





> ability to add dependencies to a job after construction
> -------------------------------------------------------
>
>                 Key: HADOOP-2086
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2086
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: mapred
>    Affects Versions: 0.14.2
>         Environment: n/a
>            Reporter: Adrian Woodhead
>             Fix For: 0.16.0
>
>         Attachments: job-add-dependencies.patch
>
>
> The current Job API only allows for dependent jobs to be passed in at object 
> construction time. It would be nice if there was an additional constructor 
> which did not take any depending jobs and then an "addDependingJob" method 
> which could be used to add depending jobs to a job at a later point.

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