如何按特定顺序终止进程？

问：

我有三个任务。 1: 2: 3:get_input (P0)clean_input (C0)find_missing (P1)

第一个任务是第二个任务的父进程，第三个任务是它自己的进程。它们应按以下顺序终止： 在 P1 找到丢失的字母并打印结果后，P1 应终止。当 P1 终止时，C0 应删除共享内存段并终止。P0 应在 C0 终止后终止。

我不确定如何正确实现这一点，因为我不太习惯 python 或多处理。

这是我到目前为止所拥有的：

import os
import multiprocessing as mp
import multiprocessing.shared_memory
import string
import sys

# Function for Task 1 (Get_Input)
def get_input(pipe, queue):
    print(f"P0 ({os.getpid()}): Task 1 (Get_Input) started.")

    sys.stdin = open(0)
    test_string = input("Enter the test string: ")

    # Send test string to child process
    pipe.send(test_string)
    
    queue.put("Task 1 (Get_Input) completed.")
    print(f"P0 ({os.getpid()}): Task 1 (Get_Input) completed.")


# Function for Task 2 (Clean_Input)
def clean_input(pipe, shm, queue):
    print(f"C0 ({os.getpid()}): Task 2 (Clean_Input) started.")

    # Receive test string from parent process
    test_string = pipe.recv()

    # Remove numbers and special characters from the test string
    cleaned_string = ''.join(filter(str.isalpha, test_string))
    print(cleaned_string)

    # Write the cleaned string into the shared memory segment
    shm.buf[:len(cleaned_string)] = cleaned_string.encode('utf-8')

    queue.put("Task 2 (Clean_Input) completed.")
    print(f"C0 ({os.getpid()}): Task 2 (Clean_Input) completed.")


# Function for Task 3 (Find_Missing)
def find_missing(shm, queue):
    print(f"P1 ({os.getpid()}): Task 3 (Find_Missing) started.")
    queue.get()  # Wait for Task 2 to complete
    
    # Read the cleaned string from the shared memory
    cleaned_string = shm.buf.tobytes().decode('utf-8')

    # Find the missing alphabets
    missing_alphabets = [ch for ch in string.ascii_lowercase if ch not in cleaned_string]

    # Print the result
    if missing_alphabets:
        print(f"P1 ({os.getpid()}): Missing alphabets: {''.join(missing_alphabets)}")
    else:
        print(f"P1 ({os.getpid()}): No missing alphabets found.")
    
    print(f"P1 ({os.getpid()}): Task 3 (Find_Missing) completed.")

if __name__ == '__main__':
    # Create a pipe for communication between P0 and C0
    parent_pipe, child_pipe = mp.Pipe()

    # Create a shared memory segment
    shm = mp.shared_memory.SharedMemory(create=True, size=1024)

    # Create a queue to control the task execution order
    task_queue = mp.Queue()

    # Create P0 (Parent Process)
    p0 = mp.Process(target=get_input, args=(parent_pipe, task_queue))
    
    # Create C0 (Child Process)
    c0 = mp.Process(target=clean_input, args=(child_pipe, shm, task_queue))
    
    # Create P1 (Another Process)
    p1 = mp.Process(target=find_missing, args=(shm, task_queue))

    # Start the processes in the desired order
    p0.start()
    c0.start()
    p1.start()
    p1.join()
    c0.join()
    p0.join()


    # Delete the shared memory segment
    shm.close()
    shm.unlink()