[IPython-dev] IPython Parallel KeyError

Dave Hirschfeld dave.hirschfeld at gmail.com
Mon Aug 5 05:12:01 EDT 2013

Min RK <benjaminrk <at> gmail.com> writes:

> Ah yes, I bet it's a bug in the --reuse flag that's not writing the new 
info to the file. if that's the case, rove
> old connection files and it should be fine.
> -MinRK
> On Aug 5, 2013, at 0:40, Dave Hirschfeld <dave.hirschfeld <at> gmail.com> 
> > MinRK <benjaminrk <at> gmail.com> writes:
> > 
> >> Sounds like a version mismatch - make sure you don't have multiple 
> > of IPython installed.  Current IPython will not write a connection file 
> > without the 'key' or 'signature_scheme' keys.
> >> 
> >> On Sun, Aug 4, 2013 at 9:06 AM, Dave Hirschfeld <dave.hirschfeld <at>
> > gmail.com> wrote:>
> >> I've updated to the latest IPython and I'm now seeing a KeyError when 
> >> to instantiate a parallel Client as neither `key` nor 
`signature_scheme` are
> >> in the `extra_args` dict.
> > 
> > Pretty sure I've just got the one IPython. The connection file was 
written by 
> > an older version of IPython than what we're running now so it sounds 
like I'll 
> > just have to recreate them? Will give that a go...
> > 
> > Thanks,
> > Dave
> > 

It's easy enough to fix (if you know what your're doing) - just change 
`exec_key` to `key` and specify the `signature_scheme` as `hmac-md5`.

In case you think it's worthwhile having it Just Work with older parallel 
configs I've opened a PR (https://github.com/ipython/ipython/pull/3904) with 
a fix that seems to work for me.

Even if the decision is to handle this in the code it probably deserves a 
note in the What's New.


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