Python多处理安全地写入文件

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GP89提到了一个很好的解决方案。使用队列将写入任务发送到对文件具有唯一写入权限的专用进程。其他所有工人均具有只读访问权限。这将消除冲突。这是一个使用apply_async的示例，但它也适用于map：

import multiprocessing as mpimport timefn = 'c:/temp/temp.txt'def worker(arg, q):    '''stupidly simulates long running process'''    start = time.clock()    s = 'this is a test'    txt = s    for i in range(200000):        txt += s     done = time.clock() - start    with open(fn, 'rb') as f:        size = len(f.read())    res = 'Process' + str(arg), str(size), done    q.put(res)    return resdef listener(q):    '''listens for messages on the q, writes to file. '''    with open(fn, 'w') as f:        while 1: m = q.get() if m == 'kill':     f.write('killed')     break f.write(str(m) + 'n') f.flush()def main():    #must use Manager queue here, or will not work    manager = mp.Manager()    q = manager.Queue()        pool = mp.Pool(mp.cpu_count() + 2)    #put listener to work first    watcher = pool.apply_async(listener, (q,))    #fire off workers    jobs = []    for i in range(80):        job = pool.apply_async(worker, (i, q))        jobs.append(job)    # collect results from the workers through the pool result queue    for job in jobs:         job.get()    #now we are done, kill the listener    q.put('kill')    pool.close()    pool.join()if __name__ == "__main__":   main()