Conquer the python3-process

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Process

Process is a process of execution of a program, is a dynamic concept, is the smallest unit of operating system scheduling.

Multiprocessing class

The process class is used to describe a processing object. When you create a subprocess, you only need to pass in a parameter that executes functions and functions to complete the process sample creation.

The Star () method starts the process

　　join() 方法实现进程间的同步，Wait for all processes to exit.

Close () is used to prevent unwanted processes from flooding the process pool to cause process blocking.

Multiprocessing. Process (Group=none, Target=none, Name=none, args= (), kwargs={}, *, Daemon=none)

Target is the function name, the function that needs to be called

The parameters required by the args function,以 tuple 的形式传入

Create Child process

Call directly

 fromMultiprocessingImportProcessImport Timedeff (name): Time.sleep (2)    Print('Hello', name)if __name__=='__main__': P= Process (Target=f, args= ('Bob',)) P.start () P.join ( )

An inherited invocation

 fromMultiprocessingImportProcessImport Timeclassmyprocess (Process):def __init__(Self,name): Super ().__init__() Self.name=namedefRun (self):Print('task <%s> is runing'%self.name) Time.sleep (2)        Print('task <%s> is done'%self.name)if __name__=='__main__': P=myprocess ('Egon') P.start ()Print('Master')

As with threads, the Run method must override

Inter-process communication

Only affinity processes are described here to communicate.

Process queue

Thread Queue shared memory space
Process queue does not share memory space, it simply passes data to achieve the purpose of interprocess communication

 fromMultiprocessingImportProcess,queueImportThreading,queuedefFun (QQ): Qq.put ("Wurui")if __name__=='__main__': Q=Queue ()#Q=queue. Queue ()P=process (Target=fun, args=(q,)) P.start ()Print(Q.get ()) P.join ()

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Pipeline Communication Pipe

 from Import Process,pipe def F (conn):    conn.send ("hello! " if__name__'__main__':    p_conn,c_conn =Pipe ()    p=process (target=f,args=c_conn)    p.start ()    Print (P_conn.recv ())    P.join ()

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Manager

A Manager object returned by Manager() controls a server process which holds Python objects and allows other processes to Mani Pulate them using proxies.

A Manager returned byManager()Would support typeslist,dict,Namespace,Lock,RLock,Semaphore,BoundedSemaphore,Condition,Event,Barrier,Queue,ValueandArray. For example:

 fromMultiprocessingImportProcess,managerImportOSdeff (d,l): D[os.getpid ()]=os.getpid () l.append (Os.getpid ())Print(L)if __name__=='__main__': With Manager () as M:d=m.dict () L=m.list (Range (5)) P_list=[]         forIinchRange (10): P=process (target=f,args=(d,l)) P.start () P_list.append (p) forJinchP_list:j.join ()Print(d)Print(l)

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Lock (Screen Lock: Prevent one process from printing complete, another process inserting)

def f (l,i):    l.acquire ()    print("hello", i)    l.release ()  if__name__'__main__':    l=Lock ( )    for in range :        Process (target=f,args= (l,i)). Start ()

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Process Pool

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Conquer the python3-process