KeyboardInterrupt vs extension written in C

[Tamas Nepusz]

Hi everyone,

I have tried to do some googling before asking my question here, but I
haven't found any suitable answer. I am developing a Python API for a
graph library written in pure C. The library is doing an awful lot of
math computations, and some of them can take a pretty long time
(depending on the size of the input). If I invoke such calculation from
Python using my own extension, the interpreter locks until the
calculation is complete (I mean, it is not responding to Ctrl-C or
SIGINT).

My question is: is there any way to allow the user to use Ctrl-C to
generate a KeyboardInterrupt and cancel such large computations? I'm
assuming that although pressing Ctrl-C may generate a KeyboardInterrupt
in Python, it is not propagated to the user level until the call into
the graph library returns. I tried to add Py_BEGIN_ALLOW_THREADS before
the call to the underlying C library and Py_END_ALLOW_THREADS after
returning from it, but I had no luck.

Thanks in advance for your answers,
--
Tamas <ntamas at gmail.com>