进程创建的两个方式进程pid 验证进程之间的空间隔离进程对象join方法进程的其他参数守护进程...

痛定思痛。 2023-10-10 10:19 54阅读 0赞

# 进程创建的两种方式 #

### 第一种方法: ###

from multiprocessing import Process import time def task(name): print(f"{name} is running") time.sleep(2) print(f"{name} is gone") if __name__ == '__main__': # 在windows环境下, 开启进程必须在__name__ == '__main__'下面 p = Process(target=task, args=("常鑫",)) # 创建一个进程对象 p.start() # 只是向操作系统发出一个开辟子进程的信号,然后就执行下一行了 # 这个信号操作系统接收到之后, 会从内存中开辟一个子进程空间, 然后再将主进程所有数据copy加载到子进程, 然后再调用CPU去执行 # 开辟子进程开销是很大的 print("==主开始") """ ==主开始 常鑫 is running 常鑫 is gone """

### 第二种方法: ###

from multiprocessing import Process import time class MyProcess(Process): def __init__(self, name): super().__init__() self.name = name def run(self): print(f"{self.name} is running") time.sleep(2) print(f"{self.name} is gone") if __name__ == '__main__': p = MyProcess('常鑫') p.start() print('===主程序') """ ===主程序 常鑫 is running 常鑫 is gone """

### 简单应用 ###

from multiprocessing import Process import time def task(name): print(f"{name} is running") time.sleep(1) print(f"{name} is gone") def task1(name): print(f"{name} is running") time.sleep(2) print(f"{name} is gone") def task2(name): print(f"{name} is running") time.sleep(3) print(f"{name} is gone") # 一个进程串行的执行三个任务 if __name__ == '__main__': start_time = time.time() task("常鑫") task1("李远点业") task2("海狗") print(f"结束时间{time.time() - start_time}") """ 常鑫 is running 常鑫 is gone 李远点业 is running 李远点业 is gone 海狗 is running 海狗 is gone 结束时间6.001969337463379 """ # 三个进程 并发或者并行的执行三个任务 if __name__ == '__main__': p1 = Process(target=task, args=("常鑫",)) p2 = Process(target=task1, args=("李远点业",)) p3 = Process(target=task2, args=("海狗",)) start_time = time.time() p1.start() p2.start() p3.start() time.sleep(5) print(f"结束时间{time.time() - start_time}") """ 常鑫 is running 李远点业 is running 海狗 is running 常鑫 is gone 李远点业 is gone 海狗 is gone 结束时间5.026661396026611 """

# 进程pid #

### 获取进程pid ###

import os import time print(f'子进程:{os.getpid()}') print(f'主进程:{os.getppid()}') time.sleep(50) # 第一次执行 """ 子进程:139000 主进程:109036 """ # 第二次执行 """ 子进程:136820 主进程:109036 """ # 第三次执行 """ 子进程:139916 主进程:109036 """

from multiprocessing import Process import os def task(name): print(f"子进程{os.getpid()}") print(f"主进程{os.getppid()}") if __name__ == '__main__': p = Process(target=task, args=("常鑫",)) p.start() print(f"===={os.getpid()}") """ ====142800 子进程143244 主进程142800 """ # 创建的进程的主进程就是 本模块此进程

# 验证进程之间的空间隔离 #

from multiprocessing import Process import time name = '太白' def task(): global name name = "刚子sb" print(f"子进程:{name}") if __name__ == '__main__': p = Process(target=task) p.start() time.sleep(3) print(f"主:{name}") """ 子进程:刚子sb 主:太白 """ # 子进程的name变量即使有global也没有重新赋值, 因为进程之间的空间隔离 lst = ["丽丽", ] from multiprocessing import Process import time def task(): lst.append('怼姐') print(f"子进程{lst}") if __name__ == '__main__': p = Process(target=task) p.start() time.sleep(3) print(f"主:{lst}") """ 子进程['丽丽', '怼姐'] 主:['丽丽'] """ # 即使是列表也有空间隔离

# 进程对象join方法 #

### 单个子进程使用join ###

join让主进程等待子进程结束之后, 在执行主进程

### 多个子进程使用join ###

#### 验证一: ####

from multiprocessing import Process import time def task(name,sec): print(f"{name} is running") time.sleep(sec) print(f"{name} is gone") if __name__ == '__main__': start_time = time.time() p1 = Process(target=task, args=("常鑫", 1)) p2 = Process(target=task, args=("李业", 2)) p3 = Process(target=task, args=("海狗", 3)) p1.start() p2.start() p3.start() p1.join() p2.join() p3.join() print(f"==主进程{time.time() - start_time}") """ 常鑫 is running 李业 is running 海狗 is running 常鑫 is gone 李业 is gone 海狗 is gone ==主进程:4.285647392272949 """

#### 验证2: ####

from multiprocessing import Process import time def task(name,sec): print(f"{name} is running") time.sleep(sec) print(f"{name} is gone") if __name__ == '__main__': start_time = time.time() p1 = Process(target=task, args=("常鑫", 1)) p2 = Process(target=task, args=("李业", 2)) p3 = Process(target=task, args=("海狗", 3)) p1.start() p2.start() p3.start() p1.join() print(f"==主进程1:{time.time() - start_time}") p2.join() print(f"==主进程2:{time.time() - start_time}") p3.join() print(f"==主进程3:{time.time() - start_time}") """ 常鑫 is running 李业 is running 海狗 is running 常鑫 is gone ==主进程1:2.2231969833374023 李业 is gone ==主进程2:3.232954502105713 海狗 is gone ==主进程3:4.242786645889282 """ # start同时开启三个进程, 同时运行 # join就是阻塞

#### 优化验证2: ####

from multiprocessing import Process import time def task(sec): print(f"子进程 is running") time.sleep(sec) print(f"子进程 is gone") if __name__ == '__main__': start_time = time.time() l1 = [] for i in range(1, 4): p = Process(target=task, args=(i,)) l1.append(p) p.start() for i in l1: i.join() print(f"==主进程{time.time() - start_time})") """ 子进程 is running 子进程 is running 子进程 is running 子进程 is gone 子进程 is gone 子进程 is gone ==主进程4.1986918449401855) """ # join就是阻塞, 主进程有join, 主进程下面的代码一律不执行, 直到进程执行完毕之后再执行

# 进程的其他参数 #

### terminate(杀死) ###

from multiprocessing import Process import time def task(name): print(f"{name} is running") time.sleep(2) print(f"{name} is gone") if __name__ == '__main__': p = Process(target=task, args=("常鑫", ), name="alex") p.start() p.terminate() print("==主进程") """ ==主进程 """ # 子进程刚发出信号就杀死 from multiprocessing import Process import time def task(name): print(f"{name} is running") time.sleep(2) print(f"{name} is gone") if __name__ == '__main__': p = Process(target=task, args=("常鑫", ), name="alex") p.start() time.sleep(1) p.terminate() print("==主进程") """ 常鑫 is running ==主进程 """ # 睡了一秒所以子进程start了

### is\_alive(判断子进程是否存活) ###

from multiprocessing import Process import time def task(name): print(f"{name} is running") time.sleep(2) print(f"{name} is gone") if __name__ == '__main__': p = Process(target=task, args=("常鑫", ), name="alex") p.start() # p.terminate() # p.join() print(p.is_alive()) print("==主进程") """ True ==主进程 常鑫 is running 常鑫 is gone """ # terminate 和 join 都会使进程结束, 所以有terminate 和 join 就会返回 False

# 守护进程 #

子进程守护着主进程, 只要主进程结束, 子进程跟着就结束

转载于:https://www.cnblogs.com/beichen123/p/11385605.html