# Python - double free or corruption error

**URL:** <https://www.ruby-forum.com/t/python-double-free-or-corruption-error/241503>\
**Category:** GNU Radio\
**Created:** [April 10, 2015, 8:51am UTC](https://www.ruby-forum.com/t/python-double-free-or-corruption-error/241503 "2015-04-10T08:51:04Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [April 10, 2015, 8:51am UTC](https://www.ruby-forum.com/t/python-double-free-or-corruption-error/241503/1 "2015-04-10T08:51:04Z")

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Hi,

when running a gnuradio application.py from the cmd line after some  
seconds the application crashs and i get the message:

\*\*\* Error in `python’: double free or corruption (fasttop): 0xaf9031c0

* * *

Iam using python 2.7.

Any ideas ?

cheers,  
Andy

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**Author:** ![andreas\_l](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/7bcc69/32.png) [@andreas\_l](https://www.ruby-forum.com/u/andreas_l)\
**Post date:** [April 10, 2015, 3:18pm UTC](https://www.ruby-forum.com/t/python-double-free-or-corruption-error/241503/2 "2015-04-10T15:18:42Z")

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On Fri, Apr 10, 2015 at 2:49 AM, Andreas L.  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> cheers,  
> Andy

It might be useful to know what your flowgraph looks like since this  
might  
be the result of a particular block. We’ve also seen issues of this when  
closing GRC, but that seems to be specific to a version of glibc.

What OS are you running? What version of glibc? Anything but canonical  
blocks in the flowgraph?

Tom

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<div class="post-metadata">

**Author:** ![andreas\_l](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/7bcc69/32.png) [@andreas\_l](https://www.ruby-forum.com/u/andreas_l)\
**Post date:** [April 11, 2015, 12:17pm UTC](https://www.ruby-forum.com/t/python-double-free-or-corruption-error/241503/3 "2015-04-11T12:17:53Z")

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Also, if you want to go deeper into debugging this, try the following  
(assuming you have a modern shell of some kind)

export MALLOC\_CHECK\_=2  
python application.py

This should make free “abort” at the point it prints out that warning.

you should then be able to

gdb --args python application.py  
run  
  
bt

to get a backtrace. For a bit more of background [1].

Greetings,  
Marcus

[1] [http://gnuradio.org/redmine/projects/gnuradio/wiki/TutorialsGDB](http://gnuradio.org/redmine/projects/gnuradio/wiki/TutorialsGDB)