1 Basic



In [1]:

    
import multiprocessing


def worker():
    """worker function"""
    print('Worker')


if __name__ == '__main__':
    jobs = []
    for i in range(5):
        p = multiprocessing.Process(target=worker)
        jobs.append(p)
        p.start()









    



Worker
Worker
Worker
Worker
Worker

2 Determining the Current Process



In [2]:

    
import multiprocessing
import time


def worker():
    name = multiprocessing.current_process().name
    print(name, 'Starting')
    time.sleep(2)
    print(name, 'Exiting')


def my_service():
    name = multiprocessing.current_process().name
    print(name, 'Starting')
    time.sleep(3)
    print(name, 'Exiting')


if __name__ == '__main__':
    service = multiprocessing.Process(
        name='my_service',
        target=my_service,
    )
    worker_1 = multiprocessing.Process(
        name='worker 1',
        target=worker,
    )
    worker_2 = multiprocessing.Process(  # default name
        target=worker,
    )

    worker_1.start()
    worker_2.start()
    service.start()









    



Process-8 Starting
worker 1 Starting
my_service Starting
Process-8 Exiting
worker 1 Exiting
my_service Exiting

3 Daemon Process



In [3]:

    
import multiprocessing
import time
import sys
def daemon():
    p = multiprocessing.current_process()
    print('Starting:',p.name, p.pid)
    sys.stdout.flush()
    time.sleep(2)
    print('Exiting:', p.name, p.pid)
    sys.stdout.flush()
    return

def non_daemon():
    p = multiprocessing.current_process()
    print('Starting:',p.name,p.pid)
    sys.stdout.flush()
    print('Exiting:',p.name,p.pid)
    sys.stdout.flush()
if __name__ == '__main__':
    d = multiprocessing.Process(
    name='daemon',target=daemon)
    d.daemon=True
    
    n = multiprocessing.Process(
    name='non-daemon', target=non_daemon)
    n.daemon=False
    d.start()
    time.sleep(1)
    n.start()









    



Starting: daemon 38548
Starting: non-daemon 38549
Exiting: non-daemon 38549
Exiting: daemon 38548

4 Terminating Process



In [5]:

    
import multiprocessing
import time
def slow_worker():
    print('Starting worker')
    time.sleep(0.1)
    print('Fininsh worker')
    return

if __name__ == '__main__':
    p = multiprocessing.Process(target=slow_worker)
    print('Before', p, p.is_alive())
    
    p.start()
    print('During',p, p.is_alive())
    
    p.terminate()
    print('Terminate:',p, p.is_alive())
    
    p.join()
    print('Join', p, p.is_alive())









    



Before <Process(Process-11, initial)> False
During <Process(Process-11, started)> True
Terminate: <Process(Process-11, started)> True
Join <Process(Process-11, stopped[SIGTERM])> False

5 SubClassing Process



In [7]:

    
import multiprocessing
class Worker(multiprocessing.Process):
    def run(self):
        print('In {}'.format(self.name))
        return

if __name__ == '__main__':
    jobs = []
    for i in range(5):
        p = Worker()
        jobs.append(p)
        p.start()
    for j in jobs:
        j.join()









    



In Worker-12
In Worker-14
In Worker-13
In Worker-15
In Worker-16



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