I tried implementing the exclusive queue as given in the Little book of semaphores. But I suspect there's a deadlock occurring as i see no progress. Not able to figure out the issue. Any pointers would be helpful.
from threading import Thread, Semaphore
class Queue:
def __init__(self):
self.leaders = 0
self.followers = 0
self.mutex= Semaphore(1)
self.leaderQ = Semaphore(0)
self.followerQ = Semaphore(0)
self.renz = Semaphore(0)
def dance(self, who, i):
print i, ' ', who, " is dancing tra ling"
def leader(self, i):
self.mutex.acquire()
if self.followers > 0:
self.followers -= 1
self.followerQ.release()
else:
self.leaders += 1
self.mutex.release()
self.leaderQ.acquire()
self.dance('leader ', i)
self.renz.acquire()
self.mutex.release()
def follower(self, i):
self.mutex.acquire()
if self.leaders > 0:
print i, " is dancing tra ling"
self.leaders -= 1
self.leaderQ.release()
else:
self.followers += 1
self.mutex.release()
self.followerQ.acquire()
self.dance('follower ', i)
self.renz.release()
class Worker(Thread):
def __init__(self, q, i):
Thread.__init__(self)
self.q = q
self.i = i
def run(self):
self.q.follower(i)
self.q.leader(i)
qu = Queue()
for i in range(2):
print('doing :', i)
Worker(qu, i).start()
