Python Multiprocess Process and Pipe Pipe usage

# _*_ encoding:utf-8 _*_
from multiprocessing import Process
 
 
# Define functions that need to be executed by child processes
def f(s):
    print(s)
 
 
# Create a global variable
x = 1
 
 
# Modify the value of a global variable inside the f2 function
def f2():
    # Use global to declare x, then modify it to 5
    global x
    x = 5
 
 
if __name__ == '__main__':
    # Create sub-processes to execute functions
    p = Process(target=f, args=('hello',))
    # Launch sub-processes
    ()
    # Waiting for a process to end
    ()
    '''
    Unlike multithreading multiple processes are independent of each other in terms of the virtual address space they use.
    '''
    # Call f2 in this process and then look at x and see that it becomes 5
    f2()
    print(x)
    # Change x back again, start a sub-process to change it.
    x = 1
    p1 = Process(target=f2)
    ()
    # Check if x is 1 or 5 in the main process #
    print(x)
    # Finding x=1 means that the child process and the master process are not seeing the same x. They are independent.
    # Since processes cannot access each other's address space，How processes communicate with each other

# _*_ encoding:utf-8 _*_
from multiprocessing import set_start_method
# Import processes, queues and pipelines
from multiprocessing import Process, Queue, Pipe
 
# Note that Queue and are not the same object #
q = Queue()
(1)
print(())
 
 
def f(q1):
    print('start')
    # Waiting for the master process to pass in a value
    print(())
    print('end')
 
 
# Pipe creates bi-directional pipes
c1, c2 = Pipe()
# Pass in data to c1 end of pipe, read it out at c2 end
('abc')
print(())
# Written on c2, read from c1 #
('xyz')
print(())
 
 
def f2(c):
    # Read the data from the connection and multiply by 2 and write it back
    (() * 2)
 
 
if __name__ == '__main__':
    '''
    set_start_method for process creation:
        fork for branch creation, spawn for spawn creation.
    '''
    set_start_method('fork', True)
    # ------------------------------
    q2 = Queue()
    # Start a child process and run it directly
    Process(target=f, args=(q2,)).start()
    # Subprocesses block to get, waiting for a value to be passed in
    (100)
    # ------------------------------
    c3, c4 = Pipe()
    # The child process will wait to write to the pipe
    Process(target=f2, args=(c4,)).start()
    # Write data from c3, then the function returns back and reads it again on c3
    (55)
    print(())