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https://issues.apache.org/jira/browse/MAPREDUCE-3162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13124791#comment-13124791
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Chris Douglas commented on MAPREDUCE-3162:
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bq. The issue here is that "startLocalizer" not only handles localizing
resources, but also mkdirs/chowns the appCachedir, log dirs, etc. So we need to
have some way of making sure that stuff happens once (preferably exactly once),
in addition to being lazy about launching the actual localizer subprocess. Does
that make any sense?
Sure. We went back and forth on this, but the operations saved by adding a fast
path for init are pretty minor (one hopes) given the cost of a container.
Asserting every precondition for container launch _on_ every container launch
is often redundant (particularly for MR), but making it idempotent seemed
cleaner than adding all the logic to avoid it. That section also has a lot of
rough patches; it's a minor crime for that neighborhood.
bq. We definitely need to move the creation of app-dirs etc out of
resource-localization.
It's a pretty inexpensive operation and pushing the dir creation into the
resource localization puts all that into a single fork for the LCE (required
root privs to create the userdir). But yea, it's usually waste.
> Separate application-init and container-init event types in NM's
> ApplicationImpl FSM
> ------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-3162
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-3162
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Affects Versions: 0.23.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Minor
> Attachments: mr-3162.txt
>
>
> Currently, the ApplicationImpl receives an INIT_APPLICATION event on every
> container initialization. Only on the first one does it really mean to init
> the application, whereas all subsequent events are for specific containers.
> This JIRA is to separate the events into INIT_APPLICATION, sent once and only
> once per application, and INIT_CONTAINER, which is sent for every container.
> The first container sends INIT_APPLICATION followed by INIT_CONTAINER.
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