python programming concurrent multi-process mutex

 

Memory space for each child process will run multiple processes are isolated from each other process data can not be shared

 

A mutex

But between processes are running on a single operating system, do not share data between processes, but share the same set of file systems, so access to the same file, or print the same terminal,

It can, and bring the competition to share the results of the competition is to bring confusion

 

# Of concurrent operation, high efficiency, but competing for the same printing terminals, print distortions brought 

from multiprocessing Import Process
 Import Time 

DEF Task (name):
     Print ( " % S 1 " % name) 
    the time.sleep ( 1 )
     Print ( " % 2 S " % name) 
    the time.sleep ( . 1 )
     Print ( " % S. 3 " % name) 



IF  the __name__ == ' __main__ ' :
     for I inRange (. 3 ): 
        P = Process (target = Task, args = ( " subprocess S% " % I,)) 
        p.start () 

'' ' 
sub-process 21 
sub-process 01 
the child 11 
sub-process 2 2 
sub-process 12 
sub-process 02 
the child 23 
sub-process 13 
sub-process 03 
'' '

 

How to control, that is, the lock processing . The mutex mutually exclusive, which means that, if more than one process compared to more than one person,

Works mutex is more than one person have to go to a competition for the same resources: the bathroom, after a man grabbed a lock on the bathroom, the others have to wait until after the completion of this task releases the lock, there may be other people there is a grab ......

So mutex principle, is to change the serial concurrency, reduces efficiency, but to ensure data security, good chaos

 

Plus there is no mutex lock is only complicated by the effect of adding a mutex will run concurrently becomes less efficient the serial

 

solve:

Import module Lock

Now the program starts all the processes will first try to steal the lock only to grab the lock in order to run 
such as run over the process to other processes continue to unlock and then grab the lock

from multiprocessing import Process, Lock
import time

def task(name, mutex):

    # 加锁
    mutex.acquire()

    print("%s 1" % name)
    time.sleep(1)
    print("%s 2" % name)
    time.sleep(1)
    print("%s 3" % name)

    # 把锁拆了
    mutex.release()


if __name__ == '__main__' : 

    # Build an object instance 
    mutex = Lock ()
     for i in the Range (3 ):
         # lock passed to the child process so that all children with the same lock 
        the p-Process = (target = Task, args = ( " child process% S " % i, mutex)) 
        p.start () 

'' ' 
now the program starts all the processes will first try to steal the lock only to grab the lock in order to run 
such as run over the process to other processes continue to unlock and then grab a lock 
' '' 

'' ' 
sub-process 01 
sub-process 02 
sub-process 03 
the child 11 
sub-process 12 
sub-process 13 
sub-process 21 
sub-process 22 
sub-process 23 
' ''

 

At the expense of efficiency, ensure good data chaos