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https://issues.apache.org/jira/browse/MAPREDUCE-4369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13403701#comment-13403701
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Bikas Saha commented on MAPREDUCE-4369:
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1) Thats because ResourceCalculatorPlugin.getResourceCalculatorPlugin() is
called multiple times and it makes to initialize it once. Also, the process id
is not available at all call sites. Ideally I would like to replace use of
ResourceCalculatorPlugin with ResourceCalculatorProcessTree in all these places
but I dont want to do cross file refactoring in a branch.
2) Thats because in the normal case the JVM_PID is defined and used. In the
local runner case, there is no JVM_PID defined and hence I chose to leave
resourceCalculator null in that case. The code knows how to deal with null
resourceCalculator but I am wary of leaving a poorly initialized resource
calculator. Until now we were lucky that the poorly initialized
resourceCalculator did not behave badly and safely ignored the null pid.
However, it would return incorrect resource values. I think its better to null
it and be explicit that it is not present vs use an invalid plugin. Also, I
have changed direct use of JVM_PID env with using the jvmContext. That leaves
the dependence of initializing task pid at 1 place(initialization of
jvmContext).
> Fix streaming job failures with WindowsResourceCalculatorPlugin
> ---------------------------------------------------------------
>
> Key: MAPREDUCE-4369
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4369
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Reporter: Bikas Saha
> Assignee: Bikas Saha
> Attachments: MAPREDUCE-4369.branch-1-win.1.patch,
> MAPREDUCE-4369.branch-1-win.2.patch
>
>
> Some streaming jobs use local mode job runs that do not start tasks trackers.
> In these cases, the jvm context is not setup and hence local mode execution
> causes the code to crash.
> Fix is to not not use ResourceCalculatorPlugin in such cases or make the
> local job run creating dummy jvm contexts. Choosing the first option because
> thats the current implicit behavior in Linux. The ProcfsBasedProcessTree
> (used inside the LinuxResourceCalculatorPlugin) does no real work when the
> process pid is not setup correctly. This is what happens when local job mode
> runs.
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