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https://issues.apache.org/jira/browse/HADOOP-3140?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12585060#action_12585060
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Amar Kamat commented on HADOOP-3140:
------------------------------------
Looks like we can optimize it further. For checking whether the task output dir
is empty or not we can do the following
{code}
if (taskOutputPath != null) {
// Get the file-system for the task output directory
FileSystem fs = taskOutputPath.getFileSystem(conf);
// Check if it exists
if (fs.exists(taskOutputPath)) {
// Get the summary for the folder
ContentSummary summary = fs.getContentSummary(taskOutputPath);
// Check if the directory contains some data
// i.e total-files + total-folders - 1(itself)
if ((summary.getFileCount() + summary.getDirectoryCount() - 1) >
0) {
shouldBePromoted = true;
}
}
}
{code}
I have tested {{fs.getContentSummary()}} via the DFSClient and it works as
expected. Comments?
> JobTracker should not try to promote a (map) task if it does not write to DFS
> at all
> ------------------------------------------------------------------------------------
>
> Key: HADOOP-3140
> URL: https://issues.apache.org/jira/browse/HADOOP-3140
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Reporter: Runping Qi
> Assignee: Amar Kamat
> Fix For: 0.17.0
>
> Attachments: HADOOP-3140-v1.patch
>
>
> In most cases, map tasks do not write to dfs.
> Thus, when they complete, they should not be put into commit_pending queue at
> all.
> This will improve the task promotion significantly.
>
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