Don't use zlib for pickle storage/persistance

[Fitblip]

Apparently on 32-bit python it has a 2GB limit for un-compressed data going in. That sucks.

joblib/joblib#122

[AsmaeBni]

I have an out of memory issue when sulley generates more than 20 000 test cases, this was fixed by using this line of code in sessions.py line 356 :

++ fh.write(zlib.compress(cPickle.dumps(data, protocol=cPickle.HIGHEST_PROTOCOL)))
-- fh.write(zlib.compress(cPickle.dumps(data, protocol=2)))

works like a charm!

[jtpereyda]

@AsmaeBni What system are you running on?

Do you know why this works? The docs say that protocol 2 is the highest protocol, so I'm a little confused on why that would fix it. https://docs.python.org/2/library/pickle.html

[AsmaeBni]

I am running on Windows 7 x64, I have actually tried with 2 but still got out of memory issues but with the suggested fix things run smoothly!

[jtpereyda]

@AsmaeBni I've got a couple requests

• What's your Python version?

• Can you provide your fuzzing script so we can see the issue?

• Also, use interactive Python on your system to see what cPickle.HIGHEST_PROTOCOL is defined as. On my system, it is 2:

  $ python
  Python 2.7.10 (default, Jun  1 2015, 18:05:38)
  [GCC 4.9.2] on cygwin
  Type "help", "copyright", "credits" or "license" for more information.
  >>> import cPickle
  >>> cPickle.HIGHEST_PROTOCOL
  2
  >>>