gistfile1.py

import pandas as pd
import multiprocessing
import numpy as np
import time
import os


print('main...')       # 这个输出为何会打印了N次？
def func(f, lock, i):
    sleeptime = round(np.random.rand() / 10, 4)
    time.sleep(sleeptime)
    print(i)
    
    lock.acquire()
    try:
        f = open('test.txt', 'a')
        try:
            f.writelines('num:{0}, sleeptime[{1}]\n'.format(i, sleeptime))
        except Exception as e:
            print(e)
        f.close()
    finally:  
        lock.release()
        

if __name__ == '__main__':
    try:
        os.remove('test.txt')
    except:
        pass
    lock = multiprocessing.Manager().Lock()
    
    print('begin...')
    #lock = multiprocessing.Lock()
    pool = multiprocessing.Pool(processes=3)

    for i in range(10):

        pool.apply_async(func, (f, lock, i))
    pool.close()
    pool.join()