Python Road 46-Multi-process

Basic use of multiple processes

Import Multiprocessingimport Osimport timedef run (): print ("Parent process:%s, child process:%s"% (Os.getppid (), Os.getpid ())) Time.sleep (2) If __name__ = = "__main__": P = multiprocessing. Process (Target=run) P.start () P.join ()

Inter-process communication

Different process memory is not shared, in order to achieve data exchange between two processes, you can use the following methods

Queue

Import Multiprocessingdef F (q): Q.put (11111) If __name__ = = "__main__": q = multiprocessing. Queue () p = multiprocessing. Process (Target=f, args= (Q,)) P.start () print (Q.get ())

Pipe

Import Multiprocessingdef F (conn): Conn.send (1) conn.send (2) print (CONN.RECV ()) Conn.close () if __name__ = = "__ Main__ ": parent_conn, Child_conn = multiprocessing. Pipe () p = multiprocessing. Process (Target=f, args= (Child_conn,)) P.start () print (PARENT_CONN.RECV ()) print (PARENT_CONN.RECV ()) Parent_con N.send (3) P.join ()

Data sharing between processes

Manager

Import Multiprocessingimport osdef func (D, L): d[os.getpid ()] = Os.getpid () print (d) l.append (Os.getpid ()) PRI NT (l) if __name__ = = "__main__": Manager = multiprocessing. Manager () d = manager.dict () L = manager.list () p_list = [] for I in range (5): p = multiprocessing. Process (Target=func, args= (d, L)) P.start () P_list.append (p) for p in P_list:p.join ()

Process Lock

Lock can avoid access violations when multiple processes are accessing shared resources

Import Multiprocessingdef F (L, I): L.acquire () print ("Hello World", i) l.release () if __name__ = = "__main__": l Ock = multiprocessing. Lock () for NUM in range: p = multiprocessing. Process (Target=f, args= (lock, num)) P.start ()

Process Pool

The process pool maintains a process queue internally, and when used, gets a process in the process pool, and if there are no processes available in the process pool, the program waits until there are processes in the process pool

Import multiprocessingimport osimport timedef foo (i): Time.sleep (2) print ("In Process", os.getpid ()) return i + 1 00def Bar (ARG): print ("==>exec done:", arg) if __name__ = = "__main__": Pool = multiprocessing.    Pool (5) for I in range: Pool.apply_async (Func=foo, args= (i,), Callback=bar) print ("End") Pool.close () Pool.join ()

This article is from the "Eight Miles" blog, so be sure to keep this source http://5921271.blog.51cto.com/5911271/1908709

Python Road 46-Multi-process