Show that an unpatched RLock blocks the native thread not just the greenlet

locks.py

from __future__ import print_function

import os
import threading
import time

import eventlet


def block(lock):
    print("Blocking")
    with lock:
        return 'ok'


def zzz(greenlet):
    print("Sleeping")
    time.sleep(1)
    if not greenlet.dead:
        greenlet.kill()


def test(key, lock):
    with lock:
        blocker = eventlet.spawn(block, lock)
        sleeper = eventlet.spawn(zzz, blocker)
        try:
            return blocker.wait()
        except eventlet.greenlet.GreenletExit as e:
            return 'killed'


def main():
    os.system('clear')

    lock = threading.RLock()
    eventlet.monkey_patch()
    # print(test('unpatched RLock', lock))

    lock = threading.RLock()
    print(test('patched RLock', lock))


if __name__ == '__main__':
    main()

output with L38 active

Blocking
<hangs>

output with L38 commented out

Blocking
Sleeping
<waits 1 second>
killed
<exits cleanly>