[IPython-dev] finding the number of available engines

[Satrajit Ghosh]

thanks min and brian.

we'll probably put this feature aside for the time being then.

two questions:

1. fernando had mentioned that there was an effort to allow creation of
engines on the fly with shwazik (i'm sure i'm spelling her name wrong). any
update on the status of this? and was it going to work with 0.10.x or was it
primarily intended for 0.11.x

2. when is the eta for a beta version of parallel operation with 0.11.x? we
would love to move over to 0.11 but waiting for the parallel stuff
currently.

cheers,

satra


On Fri, Jan 21, 2011 at 1:08 PM, Brian Granger <ellisonbg at gmail.com> wrote:

> Satra,
>
> > i've run into a related problem. i'm trying to run code on an engine that
> > can itself spawn new tasks, but i can't seem to execute function below on
> an
> > engine. it just doesn't return if you call this through the taskclient in
> > blocking mode.
>
> This usage case of recursive tasks, is not supported with the current
> twisted based code.  The reason has to do with subtle issues about how
> the Twisted event loop is run in the engines versus the client.  For
> the client, we run the Twisted event loop in a thread, which is not
> compatible with the engine, which runs it in the main thread.  This is
> probably why Min is seeing the odd GIL/thread related crash.
>
> > it seems to block in the request for the task client and multiengine
> client.
>
> Yes, this is what you would observe in the current twisted version of
> the code.  The new zeromq stuff Min has written doesn't have this
> limitation.
>
> Sorry about the hassle.
>
> Cheers,
>
> Brian
>
> > cheers,
> >
> > satra
> >
> > -----
> > def get_ipy_clients():
> >     """Get ipython clients
> >
> >     Returns client, taskclient and multiengineclient
> >     """
> >     ipyclient = None
> >     taskclient = None
> >     mecclient = None
> >     try:
> >         name = 'IPython.kernel.client'
> >         __import__(name)
> >         ipyclient = sys.modules[name]
> >     except ImportError:
> >         warn("Ipython kernel not found.  Parallel execution will be" \
> >                  "unavailable", ImportWarning)
> >     if ipyclient:
> >         try:
> >             taskclient = ipyclient.TaskClient()
> >             mecclient = ipyclient.MultiEngineClient()
> >         except Exception, e:
> >             if isinstance(e, ConnectionRefusedError):
> >                 warn("No clients found, running serially for now.")
> >             if isinstance(e, ValueError):
> >                 warn("Ipython kernel not installed")
> >     return ipyclient, taskclient, mecclient
> > ------
> >
> >
> >
> > On Wed, Jan 19, 2011 at 2:42 PM, MinRK <benjaminrk at gmail.com> wrote:
> >>
> >> mec.queue_status() returns a list of the form:
> >> [
> >>   (0, { 'pending' : "execute('a=5')", 'queue' : [ job1,job2,...] } ,
> >>   (1, {'pending' : 'None', 'queue' : [] },
> >>   ...
> >> ]
> >>
> >> In this case, engine 1 is idle.  I don't know why 1's pending is 'None'
> >> instead of None, that seems to be a bug.
> >> So you can see the idle engines with something like:
> >> def idle_engines(mec):
> >>     """return list of engine_ids corresponding to idle engines."""
> >>     qs = mec.queue_status()
> >>     engines = []
> >>     for e_id, status in qs:
> >>         if status['queue']:
> >>             continue
> >>         if not status['pending'] or status['pending'] == 'None':
> >>             engines.append(e_id)
> >>     return engines
> >> Which would return a list of engine_ids that are idle, the length of
> which
> >> would of course be the number of idle engines.
> >> -MinRK
> >>
> >>
> >> On Wed, Jan 19, 2011 at 10:39, Satrajit Ghosh <satra at mit.edu> wrote:
> >>>
> >>> hi brian and min,
> >>>
> >>> i would like to do something like this:
> >>>
> >>> if num_engines_available() > 2:
> >>>     do_x
> >>> else:
> >>>     do_y
> >>>
> >>> in 0.10.1 series is there an easy way to query how many idle engines
> are
> >>> available?
> >>>
> >>> cheers,
> >>>
> >>> satra
> >>>
> >>>
> >>> _______________________________________________
> >>> IPython-dev mailing list
> >>> IPython-dev at scipy.org
> >>> http://mail.scipy.org/mailman/listinfo/ipython-dev
> >>>
> >>
> >
> >
> > _______________________________________________
> > IPython-dev mailing list
> > IPython-dev at scipy.org
> > http://mail.scipy.org/mailman/listinfo/ipython-dev
> >
> >
>
>
>
> --
> Brian E. Granger, Ph.D.
> Assistant Professor of Physics
> Cal Poly State University, San Luis Obispo
> bgranger at calpoly.edu
> ellisonbg at gmail.com
>
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