python - python3多线程写入文件

Question

嗨，我目前是多线程新手，正在尝试解决此问题:

包含75个元素的列表

写入8个文件，且列表中的元素不超过10个(例如:file1-从索引0到9，文件2-从索引10到19，...，文件8-从索引70到74)

使用5个线程来处理，每个线程处理一个单独的文件写入，一个线程将处理1个以上的文件

一开始我只是尝试使用线程进行打印:

import threading
a = list(range(75))

class myThread(threading.Thread):
    def __init__(self, threadID, name, file_number):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.file_number = file_number

    def run(self):
        print("Starting " + self.name)
        print_time(self.name, self.file_number)
        print("Exiting " + self.name)

def print_time(threadName, file_number):
  render_list = a[:10]
  print("%s: %s" % (threadName, render_list))
  del a[:10]


# Create new threads
thread1 = myThread(1, "Thread-1", 1)
thread2 = myThread(2, "Thread-2", 2)
thread3 = myThread(3, "Thread-3", 3)
thread4 = myThread(4, "Thread-4", 4)
thread5 = myThread(5, "Thread-5", 5)
thread6 = myThread(5, "Thread-5", 6)
thread7 = myThread(5, "Thread-5", 7)
thread8 = myThread(5, "Thread-5", 8)

# Start new Threads
thread1.start()
thread2.start()
thread3.start()
thread4.start()
thread5.start()
thread6.start()
thread7.start()
thread8.start()
thread1.join()
thread2.join()
thread3.join()
thread4.join()
thread5.join()
thread6.join()
thread7.join()
thread8.join()
print("Exiting Main Thread")

它打印出完美的:

Starting Thread-1
Thread-1: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Exiting Thread-1
Starting Thread-2
Thread-2: [10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
Exiting Thread-2
Starting Thread-3
Thread-3: [20, 21, 22, 23, 24, 25, 26, 27, 28, 29]
Exiting Thread-3
Starting Thread-4
Thread-4: [30, 31, 32, 33, 34, 35, 36, 37, 38, 39]
Exiting Thread-4
Starting Thread-5
Thread-5: [40, 41, 42, 43, 44, 45, 46, 47, 48, 49]
Exiting Thread-5
Starting Thread-5
Thread-5: [50, 51, 52, 53, 54, 55, 56, 57, 58, 59]
Exiting Thread-5
Starting Thread-5
Thread-5: [60, 61, 62, 63, 64, 65, 66, 67, 68, 69]
Exiting Thread-5
Starting Thread-5
Thread-5: [70, 71, 72, 73, 74]
Exiting Thread-5
Exiting Main Thread

但是当我尝试写入文件时:

import threading
a = list(range(75))

class myThread(threading.Thread):
    def __init__(self, threadID, name, file_number):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.file_number = file_number

    def run(self):
        print("Starting " + self.name)
        print_time(self.name, self.file_number)
        print("Exiting " + self.name)

def print_time(threadName, file_number):
  render_list = a[:10]
  f = open("demofile_%s.txt" % file_number, "a")
  for i in render_list:
    f.write("%s\n" % i)
  f.close()
  print("%s: %s" % (threadName, render_list))
  del a[:10]


# Create new threads
thread1 = myThread(1, "Thread-1", 1)
thread2 = myThread(2, "Thread-2", 2)
thread3 = myThread(3, "Thread-3", 3)
thread4 = myThread(4, "Thread-4", 4)
thread5 = myThread(5, "Thread-5", 5)
thread6 = myThread(5, "Thread-5", 6)
thread7 = myThread(5, "Thread-5", 7)
thread8 = myThread(5, "Thread-5", 8)

# Start new Threads
thread1.start()
thread2.start()
thread3.start()
thread4.start()
thread5.start()
thread6.start()
thread7.start()
thread8.start()
thread1.join()
thread2.join()
thread3.join()
thread4.join()
thread5.join()
thread6.join()
thread7.join()
thread8.join()
print("Exiting Main Thread")

我文件中的内容有误，并且重复了以下打印内容:

Starting Thread-1
Starting Thread-2
Starting Thread-3
Starting Thread-4
Thread-1: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Exiting Thread-1
Thread-3: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Exiting Thread-3
Thread-4: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Exiting Thread-4
Starting Thread-5
Thread-2: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Starting Thread-5
Thread-5: [30, 31, 32, 33, 34, 35, 36, 37, 38, 39]
Exiting Thread-2
Exiting Thread-5
Thread-5: [30, 31, 32, 33, 34, 35, 36, 37, 38, 39]
Starting Thread-5
Exiting Thread-5
Starting Thread-5
Thread-5: [60, 61, 62, 63, 64, 65, 66, 67, 68, 69]
Thread-5: [60, 61, 62, 63, 64, 65, 66, 67, 68, 69]
Exiting Thread-5
Exiting Thread-5
Exiting Main Thread

似乎该线程未按打印顺序运行
希望有人可以帮助我找出问题所在

Answer 1

在开始之前，您应该了解两件事:

在Python中实际上没有多线程，因为python执行体系结构不允许多线程，因此我建议您使用LinuxC。

不保证执行顺序，调度程序按它想要的顺序执行，因此您使用了某种阻塞机制，例如信号量，以“实际”使其按您想要的顺序执行，那是因为您不知道何时有任何行将要执行，有时您需要控制系统资源。

要牢记的一个关键概念是线程是异步的，也许一个线程在创建时就可以完成，而另一个线程却在运行时没关系，因此您具有IPC(进程间通信)机制，可以对进程和线程进行正确的处理。
想象一下，您向一个网站发出请求，并且您的PC冻结直到该请求执行为止，这很烦人，因此线程不同步任务。
因此，这就是为什么您没有按顺序看到输出的答案。
现在让我们解决重复的错误:
因为不能保证执行顺序，并且您要访问没有保护的全局变量，所以您会收到不需要的错误，例如重复的数字。
您需要使用某些阻止技术来读取共享资源。