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From "Devaraj Das (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-3116) Investigate whether the array in the JobInProgress that holds TIP references can be removed
Date Fri, 28 Mar 2008 11:14:24 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-3116?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Devaraj Das updated HADOOP-3116:
--------------------------------

    Description: The array, in JobInProgress, that holds the references to TIPs is required
now only to serve the clients (web UI via JSPs and JobClient APIs, that traverse the array
and create the output). The array can now be removed since HADOOP-2119 introduces some datastructures
for running/non-running TIPs and we could probably add some more if required (e.g., for completed
TIPs). That way, we will gain when we have large jobs (many tasks) in the sense that we don't
have to go through the big array every time a client request is made. We could instead iterate
over the datastructures. Also, we should do these traversals without locking the JobTracker
to avoid cases where long traversal leads to loss of heartbeats, etc. Some staleness at the
client side (in favor of improving the JobTracker's performance) is probably okay.  (was:
The array that holds the references to TIPs is required now only to serve the clients (web
UI via JSPs and JobClient APIs, that traverse the array and create the output). The array
can now be removed since HADOOP-2119 introduces some datastructures for running/non-running
TIPs and we could probably add some more if required (e.g., for completed TIPs). That way,
we will gain when we have large jobs (many tasks) in the sense that we don't have to go through
the big array every time a client request is made. We could instead iterate over the datastructures.
Also, we should do these traversals without locking the JobTracker to avoid cases where long
traversal leads to loss of heartbeats, etc. Some staleness at the client side (in favor of
improving the JobTracker's performance) is probably okay.)
        Summary: Investigate whether the array in the JobInProgress that holds TIP references
can be removed  (was: Investigate whether the array that holds TIP references can be removed)

> Investigate whether the array in the JobInProgress that holds TIP references can be removed
> -------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-3116
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3116
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: mapred
>    Affects Versions: 0.17.0
>            Reporter: Devaraj Das
>             Fix For: 0.18.0
>
>
> The array, in JobInProgress, that holds the references to TIPs is required now only to
serve the clients (web UI via JSPs and JobClient APIs, that traverse the array and create
the output). The array can now be removed since HADOOP-2119 introduces some datastructures
for running/non-running TIPs and we could probably add some more if required (e.g., for completed
TIPs). That way, we will gain when we have large jobs (many tasks) in the sense that we don't
have to go through the big array every time a client request is made. We could instead iterate
over the datastructures. Also, we should do these traversals without locking the JobTracker
to avoid cases where long traversal leads to loss of heartbeats, etc. Some staleness at the
client side (in favor of improving the JobTracker's performance) is probably okay.

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