import os

print(‘Process (%s) start...‘ % os.getpid())
# Only works on Unix/Linux/Mac:
pid = os.fork()
if pid == 0:
    print(‘I am child process (%s) and my parent is %s.‘ % (os.getpid(), os.getppid()))
else:
    print(‘I (%s) just created a child process (%s).‘ % (os.getpid(), pid))

from multiprocessing import Process
import os

# 子进程要执行的代码
def run_proc(name):
    print(‘Run child process %s (%s)...‘ % (name, os.getpid()))

if __name__==‘__main__‘:
    print(‘Parent process %s.‘ % os.getpid())
    p = Process(target=run_proc, args=(‘test‘,))
    print(‘Child process will start.‘)
    p.start()
    p.join()
    print(‘Child process end.‘)

from multiprocessing import Pool
import os, time, random

def long_time_task(name):
    print(‘Run task %s (%s)...‘ % (name, os.getpid()))
    start = time.time()
    time.sleep(random.random() * 3)
    end = time.time()
    print(‘Task %s runs %0.2f seconds.‘ % (name, (end - start)))

if __name__==‘__main__‘:
    print(‘Parent process %s.‘ % os.getpid())
    p = Pool(4)
    for i in range(5):
        p.apply_async(long_time_task, args=(i,))
    print(‘Waiting for all subprocesses done...‘)
    p.close()
    p.join()
    print(‘All subprocesses done.‘)