[Jython-users] two questions re Pickle and Jython

[Peter M. <Pe...@re...>]

I am converting/"porting" a Python program (which runs :-)) to Jython. The
original uses the pickle module quite heavily. I have been experiencing the
following problems:

1. I can't read any of the pickled files created using Python using the same
python module/class running under Jython

2. When I convert the instance data and re-read it into a class instance
(under Jython), pickle it and then attempt to load the pickled instance, I
get inconsistent results i.e. sometimes the exact same program will load the
class instance data, pickle it OK to file and then load it OK from that file
and other times it will fail on the load. The reason this behaviour is being
noticed is that I have about 50 instances of class data, when I "convert" it
into Jython the problem seems to be with different sets of instances each
run.

Questions:

1. Has anyone any advise/experience with porting Python programs that use
pickle to Jython? Should I be able to expect to load the pickle'd instance
data from a Python run using the same module running under Jython? i.e.
without performing the conversion that I have written.

2. Any ideas as to why the same process i.e. reading in instance data,
pickle.dump and then pickle.load fails on some sets of instance data and not
others? Any good ideas on how to debug problems with pickle? :-)



I have attempted to narrow down any offending lines/pieces of data in the
conversion programs on class instances that display the failure to no avail
i.e. using a class instance that displayed the problem, I then used the
binary search method to attempt to isolate which specific piece of data was
the problem - at first the problem was there, but as I narrowed down the
problem went away! :-(

I strongly suspect the problem is in the pickle.dump process as once an set
of instance data is able to be loaded, then I can repeatedly load it time
and time again.

I have downloaded and installed the latest Jython nightly source code, so I
have the latest version of everything (including pickle) but this hasn't
solved the problem - the same problem(s) are present using Jython 2.1 or
Jython (nightly).

Thanks
Peter


Peter Milliken
Software Engineer
ResMed
Phone: +61 2 9886-5059



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