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Re: [Xgrid] Xgrid: Max size of input directory?
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Re: [Xgrid] Xgrid: Max size of input directory?

Ernie,

Yes, the program runs fine if I run it directly.  I mentioned this in a previous thread: [Xgrid] mmap and xgrid.

In testing one oddity has occurred.  The first time I submit it to the grid it runs, but it fails to write the data (using mmap).  The second time it works.  This has been the case ever since I changed the permissions on the directory where this all occurs to wide open (me(owner): read & write;  wheel: read & write;   everyone: read & write).

If I vnc to the cluster and manually create the file and then run the program, everything works.  But if I submit to Xgrid, I get this odd failure.  I have tried to create the file using open, have tried creating it and subsequently closing and then reopening it, and finally have tried creating it via the "system" function using "cp" on an existing same-size file.  And I still get failure on the first try and success on the second.

As mentioned in the earlier posts, this is a 650 MB file, so I don't want to be copying it around needlessly.

Thanks in advance for any pointers!
    Mark






On Feb 3, 2010, at 6:28 PM, Ernest N. Prabhakar, Ph.D. wrote:

Hi Mark,

On Feb 3, 2010, at 3:21 PM, Mark Spano wrote:
Ernie,

This touches on the problem I have been facing for the past week -  Kerberos and a shared filesystem work for reading large files using memory mapping and allow writing to a file (using "write").  But it appears that I cannot reliably write to it using memory mapping.  Since the files are big, I would prefer the memory mapping.  

Is memory mapping sandboxed out?

The sandbox isn't publicly documented, so I can't say for sure, but it doesn't seem like it:

$ cat /usr/share/sandbox/xgridagentd_task_somebody.sb
;;
;; _xgridtask_somebody - sandbox profile
;; Copyright (c) 2006 - 2009 Apple Inc.  All Rights reserved.
;;
;; WARNING: The sandbox rules in this file currently constitute
;; Apple System Private Interface and are subject to change at any time and
;; without notice. The contents of this file are also auto-generated and not
;; user editable; it may be overwritten at any time.
;;
(version 1)

(debug deny)

(deny default)

(import "bsd.sb")

(import "quicklookd-job-creation.sb")

(allow process* sysctl* mach* file-read* file-write* network* system-socket)
(allow signal (target pgrp))

It is more likely some quirk or interaction with the filesystem protocol; which one are you using?

I trust writing memory-mapped files works fine for you if you mount it manually from a non-Xgrid process?

-- Ernie P.

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References: 
 >[Xgrid] Xgrid: Max size of input directory? (From: charlie strauss <email@hidden>)
 >Re: [Xgrid] Xgrid: Max size of input directory? (From: "Ernest N. Prabhakar, Ph.D." <email@hidden>)
 >Re: [Xgrid] Xgrid: Max size of input directory? (From: Mark Spano <email@hidden>)
 >Re: [Xgrid] Xgrid: Max size of input directory? (From: "Ernest N. Prabhakar, Ph.D." <email@hidden>)



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