[IPython-User] some questions about parallel computing in 0.11

Maarten Derickx m.derickx.student@gmail....
Sat Aug 6 17:41:30 CDT 2011


I was just trying to turn some ideas I had for parallelizing code into
reality using the new IPython parallel interface. During this I ran
into some questions.

1.  I want to stop already running calculations (and I don't know at
the time that I start the computation if I want to abort it or after
how long I want to abort it so I cannot use timouts). But as far as I
see IPython can only abort calculations which are queued, but not yet
running. See
http://pastebin.com/VZTU9bR7
for an example where I use .abort on an asynchronous result on an
already running job.
I wonder if it's possible to stop already running jobs. I know it's
possible to shutdown engines even when they have a job, but then you
have to be able to start new ones which brings me to

2. The second thing I was wondering about and could not find in the
documentation, is if there is an easy way to do something equivalent
to "ipcluster start --n=4" and "ipengine" in python?

3. I found the following session quite unexpected, see
http://pastebin.com/EkxAArSw
The cluster was started with "ipcluster start --n=4" then I shot down
an engine while it was doing a computation and after that I cannot
start new computations
note that  c.shutdown(0) was done more that 10 seconds after the
previous command and that  c.shutdown(1) was done less then 10 seconds
after the previous command. The error in "In [34]" is ok, but the two
error's in "In [35]" and "In [36]" should not happen I guess.


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