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From "Allen Wittenauer (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-10759) Remove hardcoded JAVA_HEAP_MAX in hadoop-config.sh
Date Thu, 07 Aug 2014 13:01:14 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-10759?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14089191#comment-14089191
] 

Allen Wittenauer commented on HADOOP-10759:
-------------------------------------------

As I said before, I agree that it's a better behavior. But it's still a feature, not a bug
fix, and it's still incompatible with the existing expectations of the system.  It breaks
the principal of least surprise.... so I'm still -1 for branch-2.

For trunk, this patch is very much incomplete if we want to change how this works:
* All hard-coded values to JAVA_HEAP_MAX need to be found and removed (hadoop-config.sh, yarn,
yarn-env.sh)
* The content in hadoop-env.sh needs to get rewritten
* The content in yarn-env.sh needs to get rewritten (and a good chunk removed) ... oh yarn,
you make our lives so hard by doing the wrong thing 90% of the time... :(  On the plus side,
it perfectly demonstrates my point about the confusion with having two vars that do the same
thing....

So even with this change, JAVA_HEAP_MAX really shouldn't be exposed to users.  It's a terrible
variable name (there is no JAVA_HEAP_MIN which sets Xms, for example).  It also doesn't begin
with HADOOP_ which means it could conflict with other software.

HADOOP_HEAPSIZE has really awful semantics (forced into m's) and one really should be able
to specify your own unit.  But my concern is that it might be "too late" to fix it unless
we're very willing to break the universe.  That would probably be a common-dev@ level decision.
 (My own vote would be yes, let's break users on this one, because everyone I've ever talked
to hates the semantics here too.)

> Remove hardcoded JAVA_HEAP_MAX in hadoop-config.sh
> --------------------------------------------------
>
>                 Key: HADOOP-10759
>                 URL: https://issues.apache.org/jira/browse/HADOOP-10759
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: bin
>    Affects Versions: 2.4.0
>         Environment: Linux64
>            Reporter: sam liu
>            Priority: Minor
>             Fix For: 2.6.0
>
>         Attachments: HADOOP-10759.patch, HADOOP-10759.patch
>
>
> In hadoop-common-project/hadoop-common/src/main/bin/hadoop-config.sh, there is a hard
code for Java parameter: 'JAVA_HEAP_MAX=-Xmx1000m'. It should be removed.



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