"""Example of lock acquisition blocking forever on Linux.

Expected output is something like this:

In run(), the number is: 1
In run(), the number is: 2
In run(), the number is: 3
In print_number(), the number is: 3
In run(), the number is: 4

On Linux you get this:

In run(), the number is: 1
In run(), the number is: 2
In run(), the number is: 3
In run(), the number is: 4
In run(), the number is: 5
... going on forever

"""

import threading
import time

class MyThread(threading.Thread):
    def __init__(self):
        super(MyThread, self).__init__()
        self.running = True
        self.lock = threading.RLock()
        self._number = 0

    def run(self):
        while self.running:
            #time.sleep(0.001) #Uncomment to avoid hang on Linux
            with self.lock:
                self._number += 1
                print "In run(), the number is:", self._number
                time.sleep(0.1)

    def print_number(self):
        with self.lock:
            print "In print_number(), the number is:", self._number
            return self._number

t = MyThread()
t.start()

time.sleep(0.3)

t.print_number()

t.running = False