Python Simple Thread Pool

I should have used multiprocessing.pool.Pool orz

import time
import threading
from queue import Queue
class ThreadPool(object):
def init(self, pool_size=10):
self.pool_size = pool_size
self.jobs = []
self.job_queue = Queue()
self.result_queue = Queue()
def add_job(self, job):
    self.jobs.append(job)

def run(self):
    def worker():
        while True:
            job = self.job_queue.get()
            self.result_queue.put(job())
            self.job_queue.task_done()

    for i in range(self.pool_size):
        t = threading.Thread(target=worker)
        t.daemon = True
        t.start()

    for job in self.jobs:
        self.job_queue.put(job)

    self.job_queue.join()

def results(self):
    while not self.result_queue.empty():
        yield self.result_queue.get()

def demo():
def demo_job(job_id):
def _job():
print('Start:', job_id)
time.sleep(1)
print('End:', job_id)
return 'Return: {}'.format(job_id)
    return _job

thread_pool = ThreadPool(4)

for i in range(10):

    task = demo_job(i)
    thread_pool.add_job(task)

thread_pool.run()

for i in thread_pool.results():
    print(i)

if name == 'main':
demo()

Start: 0
Start: 1
Start: 2
Start: 3
End: 0
End: 1
Start: 4
End: 3
Start: 5
Start: 6
End: 2
Start: 7
End: 4
Start: 8
End: 7
Start: 9
End: 5
End: 6
End: 8
End: 9
Return: 1
Return: 3
Return: 0
Return: 2
Return: 4
Return: 7
Return: 5
Return: 6
Return: 8
Return: 9