| Re: Parallelise FOR loop in IDL [message #77679] |
Mon, 19 September 2011 06:58  |
Vincent Sarago
Messages: 34
Registered: September 2011
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Member |
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Hi Robin,
You may have a look on : http://www.ittvis.com/Default.aspx?tabid=1540&id=1306
I never used it, but it might works.
You can also look to :
http://www.ittvis.com/portals/0/whitepapers/IDL_MultiThread. pdf
http://slugidl.pbworks.com/w/page/29199259/Child%20Processes
Cheers,
Vincent,
On 19 sep, 14:55, Robin Wilson <ro...@rtwilson.com> wrote:
> Hi,
>
> I have some IDL code like the following, which implements a Monte Carlo
> ray-tracing model:
>
> FOR i = 0, 1000 DO BEGIN
> ; Start a new ray from source
> ; Do all sorts of complicated processing on it
> ; Record where it lands
> ENDFOR
>
> I want to be able to run it for more iterations while still keeping it
> fairly fast. If I was writing this in C I'd use OpenMP to split the
> iterations of the loop between the available cores (as they are
> independent) and then use a reduction to join all of the records of
> where the rays end up together.
>
> Is there any way to do anything like this in IDL? I've seen FastDL but
> that seems to use MPI instead (not quite what I want...) and
> unfortunately doesn't appear to be available free for academics.
>
> Any ideas?
>
> Robin
>
> ------------------
> Robin Wilson
> A PhD student studying complexity in remote sensingwww.rtwilson.com/academic
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| Re: Parallelise FOR loop in IDL [message #77757 is a reply to message #77679] |
Tue, 20 September 2011 07:29  |
H. Evans
Messages: 18
Registered: December 2009
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Junior Member |
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On Sep 19, 3:58 pm, Vincent Sarago <vincent.sar...@orange.fr> wrote:
> Hi Robin,
>
> You may have a look on :http://www.ittvis.com/Default.aspx?tabid=1540&id=1306
>
> I never used it, but it might works.
>
yes, this can be used in this context. It creates multiple bridge
objects that can run on different cores of a machine.
The memory is shared between the bridge processes, and so you are
limited to simple data structures (no objects or structures, but you
can use arrays of int, real, double, etc.). Although for the complex
data structures, it is possible to save the input/output data
structures in a save file, restore them in the bridge session, run the
processing on it, save the outputs in save files and restore them back
in the main session.
I've used it many times, but since a cock up in the installation of
IDL v8.0, it no longer works on our main CPU machines (32 core
machines). Although it does still work on the IDLv7.2 on these
machines. I have not been able to work out why IDL v8.0 doesn't start
the Bridge process.
H.
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| Re: Parallelise FOR loop in IDL [message #77781 is a reply to message #77757] |
Sun, 25 September 2011 22:48 |
MarioIncandenza
Messages: 231
Registered: February 2005
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Senior Member |
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On Sep 20, 10:29 pm, "H. Evans" <bloggs...@googlemail.com> wrote:
> I've used it many times, but since a cock up in the installation of
> IDL v8.0, it no longer works on our main CPU machines (32 core
> machines). Although it does still work on the IDLv7.2 on these
> machines. I have not been able to work out why IDL v8.0 doesn't start
> the Bridge process.
I don't have anything to add about this problem, but I was wondering,
can someone explain the software license implications of using the
IDL:IDL bridge for parallelization? Can I spawn as many IDL as I want
with my single license?
Thanks,
--Edward H.
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