Python 中的并发性（Concurrency in Python）

优质

小牛编辑

123浏览

2023-12-01

并发性经常被误解为并行性。并发意味着调度独立代码以系统方式执行。本章重点介绍使用Python执行操作系统的并发性。

以下程序有助于执行操作系统的并发性 -

import os
import time
import threading
import multiprocessing
NUM_WORKERS = 4
def only_sleep():
   print("PID: %s, Process Name: %s, Thread Name: %s" % (
      os.getpid(),
      multiprocessing.current_process().name,
      threading.current_thread().name)
   )
   time.sleep(1)
def crunch_numbers():
   print("PID: %s, Process Name: %s, Thread Name: %s" % (
      os.getpid(),
      multiprocessing.current_process().name,
      threading.current_thread().name)
   )
   x = 0
   while x < 10000000:
      x += 1
for _ in range(NUM_WORKERS):
   only_sleep()
end_time = time.time()
print("Serial time=", end_time - start_time)
# Run tasks using threads
start_time = time.time()
threads = [threading.Thread(target=only_sleep) for _ in range(NUM_WORKERS)]
[thread.start() for thread in threads]
[thread.join() for thread in threads]
end_time = time.time()
print("Threads time=", end_time - start_time)
# Run tasks using processes
start_time = time.time()
processes = [multiprocessing.Process(target=only_sleep()) for _ in range(NUM_WORKERS)]
[process.start() for process in processes]
[process.join() for process in processes]
end_time = time.time()
print("Parallel time=", end_time - start_time)

输出 (Output)

上述程序生成以下输出 -

说明 (Explanation)

“multiprocessing”是一个类似于线程模块的包。该包支持本地和远程并发。由于这个模块，程序员可以在给定系统上使用多个进程。