6 Thread Threading

1.1th Way: Threading Module 1) Single thread execution

#-*-coding:utf-8-*-Import TimedefMain ():Print("I was wrong ... ") Time.sleep (1)if __name__=="__main__": Start_time=time.time () forIinchRange (5): Main () End_time=time.time ()Print("The run time is %s"% (End_time-start_time))

　　　　

2) Multithreaded execution

• The main thread waits for all the child threads to end before they end

#-*-coding:utf-8-*- fromThreadingImportThreadImport Time#1. If multiple threads are executing the same function, they will not affect each other.defMain ():Print("I was wrong ... ") Time.sleep (1)if __name__=="__main__": Start_time=time.time () forIinchRange (5):       #Process (target=test) processes complete multitaskingt = Thread (target=main) T.start () End_time=time.time ()Print("The run time is %s"% (End_time-start_time))

　　　　

2. The difference between threads and processes

• A process is a resource-allocation unit, resource, memory, screen, etc.
• Thread is the unit of CPU dispatch

• 1 process has 1 main thread, the main thread can create multiple child threads
• The main thread task completes, waiting for the sub-thread's task to complete

　　　　　　

3.2nd way: Thread Subclass creates threads

#Coding=utf-8ImportThreadingImport TimeclassMyThread (Threading. Thread):defRun (self): forIinchRange (3): Time.sleep (1) msg="I ' m"+self.name+' @ '+STR (i)#The Name property holds the names of the current thread.            Print(msg)if __name__=='__main__': T=MyThread () T.start ( )

　　　　　　

4. Zombie process, orphan process, process No. 1th, number No. 0

1. Zombie Process: The child process ends, the parent process has not yet given it a corpse, at this time the child process becomes a zombie process
2. Orphan process: The parent process ends prematurely, without waiting for the child process to end, at which time the child process becomes an orphan process
3. Process Number No. 0 is responsible for switching tasks.
4. Process 1th is responsible for generating, destroying other sub-processes

　　　　

5. Order of execution of threads: unordered

• Execution Result: (The result of the operation may be different, but broadly consistent)

#Coding=utf-8ImportThreadingImport TimeclassMyThread (Threading. Thread):defRun (self): forIinchRange (3): Time.sleep (1) msg="I ' m"+self.name+' @ '+Str (i)Print(msg)defTest (): forIinchRange (5): T=MyThread () T.start ( )if __name__=='__main__':

　　　　

• Python interpreter masks differences in underlying hardware

　　　　

6. Summary

1. Each thread must have a name, although the above example does not specify the name of the thread object, but Python automatically assigns a name to the thread.
2. When the thread's run () method ends, the thread finishes.
3. The thread scheduler cannot be controlled, but there are other ways to influence how threads are dispatched.
4. Several states of a thread

　　　　

6 Thread Threading