[IPython-User] parallel question: how to really reset an engine

Toby Burnett tburnett@uw....
Sat Jun 23 13:59:26 CDT 2012



>From MinRK:
Restart *is* killing and restarting (the restart in the notebook/qtconsole
is literally: kill, wait, restart).

One of the things that I have long wanted to add to the engines is
KernelManager capabilities, so that they can be interrupted/restarted like
the regular Kernels.

We have a bit of degeneracy in our terminology/implementation, because what
we call a KernelManager is really two very different things: a
KernelManager, and the base KernelClient.  There should only be one
KernelManager per kernel/engine, and then one KernelClient per frontend.
This would allow remote signalling/interrupting/restarting, which we
currently don't have, and the same changes would enable the KernelManager
to be used by Engines.

Thanks for the info, and let me encourage you on this, post-0.13: that capability is essential for the notebook, and clearly would make the parallel setup more useful as a general-purpose batch facility. Currently you assume well-behaved tasks that never have memory leaks or get into infinite loops, apparently. My case invokes C++ code invoked from Python, the SWIG interface does not know how to delete all the C++ objects created during setup, partly because we never considered that we might need to.  (I've learned that it is possible to crash Linux, such that a hard reset is necessary :( )

--Toby Burnett
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