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From "Sangjin Lee (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-4958) The file localization process should allow for wildcards to reduce the application footprint in the state store
Date Tue, 26 Apr 2016 16:12:12 GMT

    [ https://issues.apache.org/jira/browse/YARN-4958?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15258346#comment-15258346
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Sangjin Lee commented on YARN-4958:
-----------------------------------

{quote}
Depends of the definition of correctly.  I defined * similar to your definition of * from
HADOOP-12747: all JARs go in the classpath. This patch also links all non-JARs from the working
directory, but they are not added to the classpath. I think that behavior is more consistent
with HADOOP-12747 than adding everything to the classpath.
{quote}

Actually there is more to it. HADOOP-12747 is orthogonal to this.

Suppose the user specified
{noformat}
-libjars lib/foo.xml
{noformat}

The intent is to upload that file to the staging directory and make it part of the task classpath.
So, (1) that file should be uploaded to the staging/libjars directory (and localized of course),
and (2) more importantly it should be made part of the task classpath. As we noted, {{libjars/*}}
will not pick up this file. Therefore the task classpath should look something like

{noformat}
libjars/*:libjars/foo.xml:...
{noformat}

In other words, non-jar entries in the libjar directory must be explicitly enumerated. I believe
this is what the {{addToClassPathIfNonJar()}} is all about. This should preserve this behavior.
I suspect the current patch does that, but was wondering if you could confirm it with a test.

bq. Didn't notice that one. What would be the best behavior? Report the aggregate file size?
The ideal behavior would be the aggregate size under the directory, but there would be complexity.
Also, given that this is an existing issue, I'm fine with filing a separate JIRA to discuss
and address it.

> The file localization process should allow for wildcards to reduce the application footprint
in the state store
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: YARN-4958
>                 URL: https://issues.apache.org/jira/browse/YARN-4958
>             Project: Hadoop YARN
>          Issue Type: Improvement
>          Components: nodemanager
>    Affects Versions: 2.8.0
>            Reporter: Daniel Templeton
>            Assignee: Daniel Templeton
>            Priority: Critical
>         Attachments: YARN-4958.001.patch
>
>
> When using the -libjars option to add classes to the classpath, every library so added
is explicitly listed in the {{ContainerLaunchContext}}'s local resources even though they're
all uploaded to the same directory in HDFS.  When using tools like Crunch without an uber
JAR or when trying to take advantage of the shared cache, the number of libraries can be quite
large.  We've seen many cases where we had to turn down the max number of applications to
prevent ZK from running out of heap because of the size of the state store entries.
> Rather than listing all files independently, this JIRA proposes to have the NM allow
wildcards in the resource localization paths.  Specifically, we propose to allow a path to
have a final component (name) set to "*", which is interpreted by the NM as "download the
full directory and link to every file in it from the job's working directory."  This behavior
is the same as the current behavior when using -libjars, but avoids explicitly listing every
file.
> This JIRA does not attempt to provide more general purpose wildcards, such as "\*.jar"
or "file\*", as having multiple entries for a single directory presents numerous logistical
issues.
> This JIRA also does not attempt to integrate with the shared cache.  That work will be
left to a future JIRA.  Specifically, this JIRA only applies when a full directory is uploaded.
 Currently the shared cache does not handle directory uploads.
> This JIRA proposes to allow for wildcards both in the internal processing of the -libjars
switch and in paths added through the {{Job}} and {{DistributedCache}} classes.
> The proposed approach is to treat a path, "dir/\*", as "dir" for purposes of all file
verification and localization.  In the final step, the NM will query the localized directory
to get a list of the files in "dir" such that each can be linked from the job's working directory.
 Since $PWD/\* is always included on the classpath, all JAR files in "dir" will be in the
classpath.



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