How do I detect if Gevent's monkey-patching is active?

Question

I have a Python unittest that depends on multiprocessing and therefore must not run when Gevent's monkey-patching is active. Is there a Python statement that can tell me whether gevent.monkey.patch_all has run or not?

Answer 1

I'm not sure there is an idiomatic way, but one simple way would be to check the socket.socket class:

import gevent.monkey, gevent.socket
gevent.monkey.patch_all()
import socket

if socket.socket is gevent.socket.socket:
    print "gevent monkey patch has occurred"

Answer 2

afaik the gevent.monkey.saved dict is only updated when an item is patched, and the original is placed within the dict (and removed on unpatching), e.g.

>>> from gevent.monkey import saved
>>> 'sys' in saved
True

Answer 3

Here's what I used for detecting if gevent monkey patching is active.

def is_gevent_monkey_patched():
    try:
        from gevent import monkey
    except ImportError:
        return False
    else:
        return bool(monkey.saved)

As A. Jesse Jiryu Davis mentioned, this works for gevent 1.0.x only.

Updated: in gevent 1.1 there's an support API that is helpful to know if objects have been monkey-patched. So the answer for gevent 1.1 could be:

def is_gevent_monkey_patched():
    try:
        from gevent import monkey
    except ImportError:
        return False
    else:
        return monkey.is_module_patched('__builtin__')

BTW, I find that monkey.is_module_patched('sys') always returns False. By looking into monkey.saved.keys() after running monkey.patch_all(), I think only the following modules are valid to check:

['_threading_local', '_gevent_saved_patch_all', 'socket', 'thread', 'ssl', 
 'signal', '__builtin__', 'subprocess', 'threading', 'time', 'os', 'select']