Python: How to detect debug interpreter

Question

How can I detect in my python script if its being run by the debug interpreter (ie python_d.exe rather than python.exe)? I need to change the paths to some dlls that I pass to an extension.

eg Id like to do something like this at the start of my python script:

#get paths to graphics dlls
if debug_build:
    d3d9Path   = "bin\\debug\\direct3d9.dll"
    d3d10Path  = "bin\\debug\\direct3d10.dll"
    openGLPath = "bin\\debug\\openGL2.dll"
else:
    d3d9Path   = "bin\\direct3d9.dll"
    d3d10Path  = "bin\\direct3d10.dll"
    openGLPath = "bin\\openGL2.dll"

I thought about adding an "IsDebug()" method to the extension which would return true if it is the debug build (ie was built with "#define DEBUG") and false otherwise. But this seems a bit of a hack for somthing Im sure I can get python to tell me...

Have you considered using raw strings to avoid excess escaping? r'bin\debug\direct3d9.dll' — cdleary
– cdleary, Commented Mar 15, 2009 at 12:46

jfs · Accepted Answer · 2009-03-16 10:39:04Z

16

Distutils use sys.gettotalrefcount to detect a debug python build:

# ...
if hasattr(sys, 'gettotalrefcount'):
   plat_specifier += '-pydebug'

this method doesn't rely on an executable name '*_d.exe'. It works for any name.
this method is cross-platform. It doesn't depend on '_d.pyd' suffix.

See Debugging Builds and Misc/SpecialBuilds.txt

edited Mar 16, 2009 at 10:39

answered Mar 15, 2009 at 4:39

jfs

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3 Comments

geometrian Over a year ago

This is an old answer, but I'm a person from the future here to confirm that this still works fine on Python 3.7.1.

myselfhimself Over a year ago

Here is an example one-liner:

python -c "import sys; sys.exit(int(hasattr(sys, 'gettotalrefcount')))" # returns 0 if is a non-debug build, 1 if is a debug build

Here is a bash test:

if [[ python -c "import sys; sys.exit(int(hasattr(sys, 'gettotalrefcount')))" ]]; then         PYTHON_DEBUG= ;     else:         PYTHON_DEBUG="y"     fi

myselfhimself Over a year ago

sorry remove the square brackets in the bash example to have it working

theller · Accepted Answer · 2009-03-14 20:25:31Z

3

Better, because it also works when you are running an embedded Python interpreter is to check the return value of

imp.get_suffixes()

For a debug build it contains a tuple starting with '_d.pyd':

# debug build:
[('_d.pyd', 'rb', 3), ('.py', 'U', 1), ('.pyw', 'U', 1), ('.pyc', 'rb', 2)]

# release build:
[('.pyd', 'rb', 3), ('.py', 'U', 1), ('.pyw', 'U', 1), ('.pyc', 'rb', 2)]

answered Mar 14, 2009 at 20:25

theller

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Comments

John Feminella · Accepted Answer · 2009-03-14 19:24:01Z

2

An easy way, if you don't mind relying on the file name:

if sys.executable.endswith("_d.exe"):
  print "running on debug interpreter"

You can read more about the sys module and its various facilities here.

answered Mar 14, 2009 at 19:24

John Feminella

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