Python通過隊列來實現(xiàn)進程間通信

from multiprocessing import Process
import os
import time

nums = [11, 22]


def work1():
  """子進程要執(zhí)行的代碼"""
  print("in process1 pid=%d ,nums=%s" % (os.getpid(), nums))
  for i in range(3):
    nums.append(i)
    time.sleep(1)
    print("in process1 pid=%d ,nums=%s" % (os.getpid(), nums))


def work2():
  """子進程要執(zhí)行的代碼"""
  print("in process2 pid=%d ,nums=%s" % (os.getpid(), nums))


if __name__ == '__main__':
  p1 = Process(target=work1)
  p1.start()
  p1.join()

  p2 = Process(target=work2)
  p2.start()

from multiprocessing import Queue
# 初始化一個Queue對象，最多可接收三條put消息
q = Queue(3) 
q.put("消息1")
q.put("消息2")
print(q.full()) # False
q.put("消息3")
print(q.full()) # True

# 因為消息隊列已滿下面的try都會拋出異常
# 第一個try會等待2秒后再拋出異常
try:
  q.put("消息4", True, 2)
except:
  print("消息隊列已滿，現(xiàn)有消息數(shù)量:%s" % q.qsize())
# 第二個Try會立刻拋出異常
try:
  q.put_nowait("消息4")
except:
  print("消息列隊已滿，現(xiàn)有消息數(shù)量:%s" % q.qsize())

# 推薦的方式，先判斷消息列隊是否已滿，再寫入
if not q.full():
  q.put_nowait("消息4")

# 讀取消息時，先判斷消息列隊是否為空，再讀取
if not q.empty():
  for i in range(q.qsize()):
    print(q.get_nowait())

from multiprocessing import Process, Queue
import os
import time
import random


def write(q):
  # 寫數(shù)據(jù)進程執(zhí)行的代碼:
  for value in ['A', 'B', 'C']:
    print('Put %s to queue...' % value)
    q.put(value)
    time.sleep(random.random())


def read(q):
  # 讀數(shù)據(jù)進程執(zhí)行的代碼:
  while True:
    if not q.empty():
      value = q.get(True)
      print('Get %s from queue.' % value)
      time.sleep(random.random())
    else:
      break


if __name__ == '__main__':
  # 父進程創(chuàng)建Queue，并傳給各個子進程：
  q = Queue()
  pw = Process(target=write, args=(q,))
  pr = Process(target=read, args=(q,))
  # 啟動子進程pw，寫入:
  pw.start()
  # 等待pw結(jié)束:
  pw.join()
  # 啟動子進程pr，讀取:
  pr.start()
  pr.join()
  print('')
  print('所有數(shù)據(jù)都寫入并且讀完')