Example of debugging Cython project
Set-up environment, for example using vagrant
$ vagrant init debian/jessie64
$ vagrant up
$ vagrant ssh
$ sudo apt-get install build-essential python-dbg git gdb \
python-setuptools python-pip python-dev
$ sudo /usr/bin/python-dbg /usr/bin/pip install cython
$ python-dbg --version
Python 2.7.9
$ python --version
Python 2.7.9
$ python3
-bash: python3: command not found
$ cython --version
Cython version 0.25.2
[89796 refs]
$ gdb --version
GNU gdb (Debian 7.7.1+dfsg-5) 7.7.1
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word".
$ gdb --configuration
This GDB was configured as follows:
configure --host=x86_64-linux-gnu --target=x86_64-linux-gnu
--with-auto-load-dir=$debugdir:$datadir/auto-load
--with-auto-load-safe-path=$debugdir:$datadir/auto-load
--with-expat
--with-gdb-datadir=/usr/share/gdb (relocatable)
--with-jit-reader-dir=/usr/lib/gdb (relocatable)
--without-libunwind-ia64
--with-lzma
--with-python=/usr (relocatable)
--with-separate-debug-dir=/usr/lib/debug (relocatable)
--with-system-gdbinit=/etc/gdb/gdbinit
--with-zlib
--without-babeltrace
("Relocatable" means the directory can be moved with the GDB installation
tree, and GDB will still find it.)
Get the source code:
git clone https://github.com/dfroger/cygdb-demo
cd cygdb-demoBuild:
python-dbg setup.py build_ext --inplacedemo.pyx compiles to demo.c and cython_debug/cython_debug_info_demo
For readiblity, cython_debug_info_demo has been formatted bellow with:
sudo apt-get install libxml2-utils
xmllint --format --recover cython_debug_info_demo > out.xmlcdef double foo(double x):
return 2*xcompiles to:
static double __pyx_f_4demo_foo(double __pyx_v_x)debug info:
<Function cname="__pyx_f_4demo_foo" lineno="1" name="foo" pf_cname="" qualified_name="demo.foo">
<Locals>
<LocalVar cname="__pyx_v_x" lineno="1" name="x" qualified_name="demo.foo.x" type="CObject"/>
</Locals>
<Arguments>
<x/>
</Arguments>
<StepIntoFunctions/>
</Function>def bar(double x):
return 2*xcompiles to:
static PyObject *__pyx_pw_4demo_1bar(PyObject *__pyx_self, PyObject *__pyx_arg_x)
static PyObject *__pyx_pf_4demo_bar(CYTHON_UNUSED PyObject *__pyx_self, double __pyx_v_x)debug info:
<Function cname="__pyx_pw_4demo_1bar" lineno="4" name="bar" pf_cname="" qualified_name="demo.bar">
<Locals>
<LocalVar cname="__pyx_v_x" lineno="4" name="x" qualified_name="demo.bar.x" type="CObject"/>
</Locals>
<Arguments/>
<StepIntoFunctions/>
</Function>cpdef double baz(double x):
return 2*xcompiles to:
static PyObject *__pyx_pw_4demo_3baz(PyObject *__pyx_self, PyObject *__pyx_arg_x)
static PyObject *__pyx_pf_4demo_2baz(CYTHON_UNUSED PyObject *__pyx_self, double __pyx_v_x)
static double __pyx_f_4demo_baz(double, int __pyx_skip_dispatch)debug info:
<Function cname="__pyx_f_4demo_baz" lineno="7" name="baz" pf_cname="__pyx_pw_4demo_3baz" qualified_name="demo.baz">
<Locals>
<LocalVar cname="__pyx_v_x" lineno="7" name="x" qualified_name="demo.baz.x" type="CObject"/>
</Locals>
<Arguments>
<x/>
</Arguments>
<StepIntoFunctions/>
</Function>Run debugger:
$ cygdb . -- --args python-dbg main.py
Set up a breakpoint, and run:
cy break foo
cy run
cy list
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