如何在代码中使用多处理更改多线程(Python)

Question

我写了一个程序，用python实现了线程和队列的caesar-cipher。我想在我的代码中用多处理来改变所有的线程工作，但我不知道该怎么做。如果您能解释一下在哪里以及如何开始实现，我将不胜感激。代码如下：

import threading
import Queue
import sys
import string

lock = threading.Lock()
def do_work(in_queue, out_queue, shift):
    while True:
        lock.acquire()
        item = in_queue.get()
        result = caesar(item, shift)
        out_queue.put(result)
        in_queue.task_done()
        lock.release()
def caesar(plaintext, shift):
    plaintext = plaintext.upper()
    alphabet = string.ascii_uppercase
    shifted_alphabet = alphabet[shift:] + alphabet[:shift]
    table = string.maketrans(alphabet, shifted_alphabet)
    return plaintext.translate(table)

if __name__ == "__main__":
    if len(sys.argv) != 4:
        print("Duzgun giriniz: '<filename>.py s n l'")
        sys.exit(0)
    else:
        s = int(sys.argv[1])
        n = int(sys.argv[2])
        l = int(sys.argv[3])

    work = Queue.Queue()
    results = Queue.Queue()
    myfile=open('metin.txt','r')
    text_data=myfile.read() # <=== here load file
    index=0

    for i in xrange(n):
        t = threading.Thread(target=do_work, args=(work, results, s))
        t.daemon = True
        t.start()

    for i in range(0, len(text_data), l):
        work.put(text_data[index:index + l])
        index += l

    work.join()

    index=0
    output_file=open("crypted"+ "_"+ str(s)+"_"+str(n)+"_"+str(l)+".txt", "w")
    for i in range(0, len(text_data), l):
        output_file.write(results.get())
        index += l
    sys.exit()

Answer 1

您可以节省一些代码，转而使用标准的multiprocessing.Pool实现。

import multiprocessing
import sys
import string
import itertools

# for non-forking systems like Windows
def worker(args):
    # args: (text, shift)
    return caesar(*args)

# for forking systems like linux
def forking_worker(args):
    # args: ((start_index, end_index), shift)
    return caesar(text_data[args[0][0]:args[0][1], args[1])

def caesar(plaintext, shift):
    plaintext = plaintext.upper()
    alphabet = string.ascii_uppercase
    shifted_alphabet = alphabet[shift:] + alphabet[:shift]
    table = string.maketrans(alphabet, shifted_alphabet)
    return plaintext.translate(table)

if __name__ == "__main__":
    if len(sys.argv) != 4:
        print("Duzgun giriniz: '<filename>.py s n l'")
        sys.exit(0)
    else:
        s = int(sys.argv[1])
        n = int(sys.argv[2])
        l = int(sys.argv[3])

    pool = multiprocessing.Pool() # todo: change number of cpus...
    with open('metin.txt') as myfile:
        text_data=myfile.read() # <=== here load file

    # on a forking system so only pass index, not text to child
    result = pool.map(forking_worker, 
        zip(((index, index + l)
            for index in range(0, len(text_data), l)),
            itertools.cycle([s])))

    with open("crypted"+ "_"+ str(s)+"_"+str(n)+"_"+str(l)+".txt", "w") as output_file:
        output_file.writelines(result)