Python 51st days ---- thread, Event, queue, python 51st days

Python 51st days ---- thread, Event, queue, python 51st days

Differences between processes and threads:

Thread = instruction set, process = resource set (thread set)

1. threads in the same process share the memory space. The process and process are independent.

2. threads in the same process can communicate directly. inter-process communication must be implemented through an intermediate proxy.

3. The creation thread is simple. The process is a clone parent process.

4. One thread can control and operate other threads in the same process, but the process can only operate sub-processes.

5. Fast thread startup and slow process startup

Thread example:

1 import time, threading 2 3 def run (attr): 4 print ('output: ', attr) 5 time. sleep (3) 6 7 8 t1 = threading. thread (target = run, args = ('first thread',) 9 t2 = threading. thread (target = run, args = ('second thread',) 10 11 t1.start () # Start Thread 112 t2.start () # Start Thread 2

1 def run2 (attr): 2 print ('output: ', attr) 3 time. sleep (3) 4 5 run2 ('first thread') 6 run2 ('second thread') 7 # convert the above into series execution

 

Inherited thread-class write thread

1 #! Usr/bin/env python 2 #-*-coding: UTF-8-*-3 # Author calmyan 4 5 import threading, time 6 7 class thre (threading. thread): # inherit the Class 8 def _ init _ (self, n, times) in the Thread: 9 super (thre, self ). _ init _ () 10 self. n = n11 self. teims = times12 def run (self): 13 print ('execution first thread: ', self. n) 14 time. sleep (self. teims) 15 16 star_time = time. time () 17 t1 = thre ('first thread', 3) 18 t2 = thre ('second thread', 4) 19 t1.start () 20 t2.start () 21 t1.join () # join wait for the thread to finish executing 22 23 t2.join () 24 den_time = time. time ()-star_time25 print (den_time)

 

 

Wait until the thread execution is complete and use. join

1 import time, threading 2 lock = threading. lock () # define a thread lock variable 3 def run (attr): 4 Lock. acquire () # apply for a thread lock 5 global num 6 print ('output: ', attr) 7 # time. sleep (3) 8 num + = 1 9 lock. release () # release thread lock 10 time. sleep (3) 11 print ('output finished '. center (10, 'two') 12 star_time = time. time () # Start time 13 14 num = 015 re_lilst = [] # define a list 16 for I in range (50): 17 t1 = threading. thread (target = run, args = ('% s Thread' % I),) # create Thread 18 # t1.setDaemon (True) # Set as Daemon. When the main thread is completed, the daemon also stops 19 t1.start () # Start thread 20 re_lilst.append (t1) # Do not use JOIN to avoid blocking as serial 21 22 print (threading. current_thread (), threading. active_count () # view the main sub-active thread of the thread 23 # print ('sub-thread '. center (40, '☆') 24 print ('digit: ', num) 25 for I in re_lilst: # Wait for the thread to finish 26 I. join () 27 print ('Number: ', num) 28 print ('main thread '. center (60, '◇ '), threading. current_thread (), threading. active_count () 29 30 den_time = time. time ()-star_time # Total time 31 print (den_time)

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The daemon process is equivalent to a subordinate of the main process. When the main process ends, it will stop no matter whether the execution in the daemon process is complete or not!

1 import time, threading 2 lock = threading. lock () # define a thread lock variable 3 def run (attr): 4 Lock. acquire () # apply for a thread lock 5 global num 6 print ('output: ', attr) 7 8 # time. sleep (3) 9 num ++ = 110 lock. release () # release the thread lock 11 time. sleep (3) 12 print ('output finished '. center (10, 'two') 13 14 star_time = time. time () # Start time 15 16 num = 017 re_lilst = [] # define a list 18 for I in range (50): 19 t1 = threading. thread (target = run, args = ('% s Thread' % I),) # create Thread 20 t1.setDaemon (True) # set as daemon when the main Thread is completed, the daemon also stops 21 t1.start () # Starts thread 22 re_lilst.append (t1) # does not need to JOIN to avoid blocking as serial 23 24 print (threading. current_thread (), threading. active_count () # view the main sub-active thread of the thread 25 # print ('sub-thread '. center (40, '☆') 26 print ('digit: ', num) 27 # for I in re_lilst: # Wait for the thread to finish 28 # I. join () 29 print ('Number: ', num) 30 print ('main thread '. center (60, '◇ '), threading. current_thread (), threading. active_count () 31 32 den_time = time. time ()-star_time # Total time 33 print (den_time)

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Thread lock, which is not used in py3:

Lock = threading. Lock ()

Lock. acquire ()

Recursive lock for Recursive threads

1 import time, threading 2 3 def run (I): 4 print ('output: ------- ', I) 5 lock. acquire () # apply for lock 6 global num1 7 num1 + = 1 8 time. sleep (0.1) 9 lock. release () # release lock 10 return num111 12 def run2 (I): 13 lock. acquire () # apply for Lock 14 global num215 print ('output: 22', I) 16 num2 + = 117 time. sleep (0.1) 18 lock. release () # release lock 19 return num220 21 def run3 (I): 22 lock. acquire () # apply for Lock 23 res = run (I) 24 print ('output: 333 ', I) 25 res2 = run2 (I) 26 time. sleep (0.1) 27 print (res, res2) 28 lock. release () # release lock 29 30 31 if _ name _ = '_ main _': 32 star_time = time. time () # Start time \ 33 num1, num2 = 0,034 # lock = threading. lock () # defines a thread lock. If it is a thread Lock, an error occurs in recursion. 35 lock = threading. RLock () # define a recursive lock 36 37 for I in range (10): 38 # t1 = threading. thread (target = run, args = ('% s Thread' % I),) # create Thread 39 t1 = threading. thread (target = run3, args = ('% s Thread' % I),) # create Thread 40 t1.start () # Start Thread 41 42 else: 43 print ('number of active threads: ', threadin G. active_count () # view the number of active threads in the thread 44 45 46 while threading. active_count ()! = 1: # there is not only one thread, that is, determine whether there is the remaining main thread 47 # print (threading. active_count () # view the number of active threads 48 pass49 else: 50 print ('main thread: pid, number of active Threads '. center (60, '◇ '), threading. current_thread (), threading. active_count () #51 den_time = time. time ()-star_time # Total time 52 print (den_time) 53 print (num1, num2)

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Semaphores are equivalent to multiple thread locks.

1 #! Usr/bin/env python 2 #-*-coding: UTF-8-*-3 # Author calmyan 4 5 #! Usr/bin/env python 6 #-*-coding: UTF-8-*-7 # Author calmyan 8 import time, threading 9 10 def run (attr): 11 semaphore. acquire () # apply for a semaphore thread lock 12 global num13 print ('output: ', attr) 14 time. sleep (1) 15 semaphore. release () # release the semaphore thread lock 16 17 star_time = time. time () # Start time 18 if _ name _ = '_ main _': 19 20 semaphore = threading. boundedSemaphore (4) # semaphore allows a maximum of several threads to run simultaneously (multiple locks) 21 for I in range (50): 22 t1 = threading. thread (target = run, ar Gs = ('% s thread' % I),) # create thread 23 t1.start () # Start thread 24 25 while threading. active_count ()! = 1: # there is not only one thread, that is, determine whether there is the remaining main thread 26 pass27 else: 28 print ('main thread '. center (60, '◇ '), threading. current_thread (), threading. active_count () 29 den_time = time. time ()-star_time # Total time 30 print (den_time)

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Event thread flag

Traffic Light example

1 #! Usr/bin/env python 2 #-*-coding: UTF-8-*-3 # Author calmyan 4 5 import threading, time 6 7 event = threading. event () # generate an identifier object 8 def lighter (): #9 count = 0 # define time SECONDS 10 event. set () # set flag 11 while True: 12 if count> 9 and count <15: # set to red light 13 event. clear () # clear the flag, 14 print ('\ 033 [41; 1 m turns to a red light! \ 033 [0m') 15 elif count> = 15 and count <18: # For yellow light 16 17 print ('\ 033 [43; 1 m to yellow light! \ 033 [0m') 18 elif count> = event. set () # set flag 20 print ('\ 033 [42; 1 m to green! \ 033 [0m') 21 count = 0 # re-timing 22 else: 23 print ('\ 033 [42; 1 m green .....! \ 033 [0m') 24 time. sleep (1) 25 count + = 1 # Add 26 27 28 def car (name): 29 while True: 30 if event every second. is_set (): # if there is a sign, it indicates that the green light 31 print ('[% s] is driving .... '% name) 32 time. sleep (1) 33 else: 34 print ('[% s] waiting ..... '% name) 35 event. wait () # wait for the 36 print sign to be obtained ('green light, [% s] continue driving... '% name) 37 time. sleep (1) 38 39 40 light = threading. thread (target = lighter,) # define a Thread 41 light. start () # start thread 42 43 car1 = threading. thread (target = car, args = ('hongqi marker',) # generate a car Thread 44 car1.start ()

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Queue producer consumer model

 

1 #! Usr/bin/env python 2 #-*-coding: UTF-8-*-3 # Author calmyan 4 5 # queue producer consumer model 6 7 import threading, time, queue 8 9 q = queue. queue () # create a Queue 10 11 def produ (name): # Production Function 12 count = 013 while True: 14 bz = name + str (count) 15 q. put (bz) 16 print ('[% s] produced, number of [% s] g steamed stuffed bun' % (name, count, bz )) 17 count ++ = 118 time. sleep (1.5) 19 20 def consump (name): # consumer 21 while True: 22 I = q. get () # get 23 print ('[% s] get steamed stuffed bun [% s], and eat' % (name, I) 24 time. sleep (0.5) 25 26 27 p1 = threading. thread (target = produ, args = ('wang Wu Bao sub-Shop ',) # create a new Thread producer 28 p2 = threading. thread (target = produ, args = ('mahjong six package pload',) # create a new Thread producer 29 r1 = threading. thread (target = consump, args = ('zhang san',) # create a new Thread consumer 30 r2 = threading. thread (target = consump, args = ('lily',) # create a new Thread consumer 31 p1.start () 32 p2.start () 33 r1.start () 34 r2.start ()

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