Dan,
thanks a lot; this is very helpful information!
Jan.
On Mon, Mar 8, 2010 at 11:01 PM, Dan Bron <[email protected]> wrote:
> Jan Jacobs asked:
> > is it possible for a master J-session to initiate other J-sessions that
> run
> > on separate cores
>
> Sure. For example, the follow lines will execute a fresh J session:
>
> require 'task'
> fork BINPATH_z_, PATHSEP_j_ (, }.~ [ i:~ ,) >{.ARGV_z_
>
> Of course it's up to the OS to assign tasks to cores appropriately (which
> OSes are pretty good at).
>
> In terms of having these new tasks do something useful, the simplest way is
> to keep them independent (ie. no sharing of data), and
> simply control their execution through extra command line parameters.
>
> If you must share data, or even pass messages, then you're pursuing coarse
> parallelism, which has been discussed in some depth
> recently. For example, see this thread:
>
> http://www.jsoftware.com/pipermail/chat/2010-February/003190.html
>
> (which references a number of previous threads on the same or related
> topics.) That thread resulted in a Wiki initiative to
> implement a (user-level, coarse) parallelism utility in J. Don has started
> collecting ideas for that implementation on the Wiki:
>
> http://www.jsoftware.com/jwiki/MultiCoreSupport
>
> Since it's a favorite of Devon's, we also discuss this topic frequently in
> the NYC JUG, so you might try searching the minutes of
> our meetings on the Wiki as well (I mean visually -- a lot of our notes are
> scanned in as images, rather than being transcribed as
> text).
>
> But in short, at the moment there's nothing off-the-shelf to help
> distribute J workload. If you have an immediate need, you'll have
> to roll something of your own. Shared mapped files (for large data) and
> sockets (for asynchronous alerts or messages) provide good
> starting points. There may be some examples or demonstrations of this in
> the Forum archives, if you dig a little.
>
> -Dan
>
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Jan Jacobs
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