python 多进程记录

1、multiprocessing模块

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())
   # dst=['train','test','valid']
    p = Process(target=run_proc, args=('test',))
    print ('Process will start.')
    p.start()
    p.join()
    print ('Process end.')

结果：

Parent process 3728.
Process will start.
Run child process test (13004)...
Process end.

 

2、Pool 进程池（进程池的方式批量创建子进程）

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()
    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.')

结果：

Parent process 3692.
Waiting for all subprocesses done...
Run task 0 (2632)...
Run task 1 (8528)...
Run task 2 (10076)...
Run task 3 (10904)...
Run task 4 (4504)...
Task 3 runs 0.81 seconds.
Task 2 runs 2.00 seconds.
Task 0 runs 2.27 seconds.
Task 4 runs 2.69 seconds.
Task 1 runs 2.81 seconds.
All subprocesses done