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

Answer 1

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

Answer 2

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)]

Answer 3

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.