The sys module contains __excepthook__ to recover sys.excepthook if necessary. The same is not present in the threading module, even if threading.excepthook is exposed.

Can't you do that in your own hook? For example:

orig_hook = threading.excepthook
threading.excepthook = myhook

def myhook(args):
   try:
      ...
   except:
      print("too bad!")
      orig_hook(args)


I found one interesting usage of sys.__excepthook__ in code.InteractiveInterpreter:

        if sys.excepthook is sys.__excepthook__:
            lines = traceback.format_exception_only(type, value)
            self.write(''.join(lines))
        else:
            # If someone has set sys.excepthook, we let that take precedence
            # over self.write
            sys.excepthook(type, value, tb)

So it seems like sys.__excepthook__ is useful ;-)

> I found one interesting usage of sys.__excepthook__ in code.InteractiveInterpreter:

That is exactly what I wished this was there for hehe. We are installing a custom version of excepthook and wanted to check if the user had changed it.

New changeset 750c5abf43b7b1627ab59ead237bef4c2314d29e by Mario Corchero in branch 'master':
bpo-42308: Add threading.__excepthook__ (GH-23218)
https://github.com/python/cpython/commit/750c5abf43b7b1627ab59ead237bef4c2314d29e

PR merged, thanks Mario.