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https://issues.apache.org/jira/browse/MAPREDUCE-6473?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15092816#comment-15092816
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Kuhu Shukla commented on MAPREDUCE-6473:
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Thanks [~eepayne] for your comments.
In the above scenario when thread 2 comes along and finds that the provider
list is null , since thread 1 is already in the synchronized block, thread 2
will wait and enter it only when thread 1 is done. Once it does get into the
block, an additional check of whether the list is null or not helps thread 2 to
not do the same work again. Please let me know if this helps or if I am missing
anything? Thanks a lot again.
> Job submission can take a long time during Cluster initialization
> -----------------------------------------------------------------
>
> Key: MAPREDUCE-6473
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6473
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: performance
> Reporter: Kuhu Shukla
> Assignee: Kuhu Shukla
> Attachments: 99%ile.png, MAPREDUCE-6473-PerfTest.txt,
> MAPREDUCE-6473-v1.patch, MAPREDUCE-6473-v2.patch, MAPREDUCE-6473-v3.patch,
> MAPREDUCE-6473-v4.patch, MAPREDUCE-6473-v5.patch, MAPREDUCE-6473-v6.patch,
> avgtime.png
>
>
> During initialization in Cluster.java, the framework provider classes are
> loaded inside a sync block which can considerably increase job submission
> time when the number of submissions are high. The motive is to reduce time
> spent in this sync block safely to improve performance.
> {noformat}
> synchronized (frameworkLoader) {
> for (ClientProtocolProvider provider : frameworkLoader) {
> LOG.debug("Trying ClientProtocolProvider : "
> + provider.getClass().getName());
> {noformat}
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