This post might help a bit.
On Mon, Oct 21, 2013 at 11:11 AM, Harsh J <[EMAIL PROTECTED]> wrote:
> The dirs in that env-var are app-specific and are for the app's user
> to utilize. You shouldn't have any permission issues working within
> The LocalDirAllocator is still somewhat MR-bound but you can still be
> able to make it work by giving it a config with the values it needs.
> On Mon, Oct 21, 2013 at 8:49 PM, John Lilley <[EMAIL PROTECTED]>
> > Thanks again. This gives me a lot of options; we will see what works.
> > Do you know if there are any permissions issues if we directly access
> the folders of LOCAL_DIR_ENV?
> > Regarding LocalDirAllocator, I see its constructor:
> LocalDirAllocator(String contextCfgItemName) and a note mentioning that an
> example of this item is "mapred.local.dir". Is that the correct usage, or
> is there something YARN-generic?
> > Cheers,
> > john
> > -----Original Message-----
> > From: Harsh J [mailto:[EMAIL PROTECTED]]
> > Sent: Sunday, October 20, 2013 11:58 PM
> > To: <[EMAIL PROTECTED]>
> > Subject: Re: temporary file locations for YARN applications
> > Hi,
> > MR does use multiple disks when spilling. But the work directory is also
> round-robined to spread I/O.
> > YARN sets an environment property thats a list (comma separated value)
> of directories (ApplicationConstants.LOCAL_DIR_ENV) your app container can
> together use. Perhaps read it in with
> > and then round robin internally over those paths (with free space
> > Perhaps you can even reuse the org.apache.hadoop.fs.LocalDirAllocator
> > class; which is what MR uses. Its not been declared publicly stable
> though, but we can do that over a JIRA.
> > On Mon, Oct 21, 2013 at 2:05 AM, John Lilley <[EMAIL PROTECTED]>
> >> Harsh, thanks for the quick response. These files don't need to be on
> the DFS (although we use that too). These are local files used during
> sorting, joining, transitive closure.
> >> The task-relative folder might be good enough, but our app *can* make
> use of multiple temp folders if they are available. Our YARN app can be
> fairly I/O intensive; is it possible to allocate more than one temp folder
> on different physical devices?
> >> Or perhaps YARN might help us. Will YARN assign tasks to CWD folders on
> different disks so that they do not compete with each other on I/O?
> >> For that matter, where does MR allocate the temporary files generated
> by Mapper output? Presumably MR has the same I/O parallelism requirements
> that we do.
> >> Thanks
> >> John
> >> -----Original Message-----
> >> From: Harsh J [mailto:[EMAIL PROTECTED]]
> >> Sent: Sunday, October 20, 2013 10:49 AM
> >> To: <[EMAIL PROTECTED]>
> >> Subject: Re: temporary file locations for YARN applications
> >> Every container gets its own local work directory (You can use the
> relative ./) thats auto-cleaned up at the end of the container's life.
> >> This is the best place to store the temporary files. This is not
> something you need custom configuration for.
> >> Do the files need to be on a distributed FS or a local one?
> >> On Sun, Oct 20, 2013 at 8:54 PM, John Lilley <[EMAIL PROTECTED]>
> >>> We have a pure YARN application (no MapReduce) that has need to store
> >>> a significant amount of temporary data. How can we know the best
> >>> location for these files? How can we ensure that our YARN tasks have
> >>> write access to these locations? Is this something that must be
> configured outside of YARN?
> >>> Thanks,
> >>> John
> >> --
> >> Harsh J
> > --
> > Harsh J
> Harsh J
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