Python中透過threading模組定義和呼叫線程

定義執行緒

最簡單的方法：使用target指定執行緒要執行的目標函數，再使用start()啟動。

語法：

class threading.Thread(group=None, target=None, name=None, args=(), kwargs={})

group恆為None，保留未來使用。 target為要執行的函數名。 name為執行緒名，預設為Thread-N，通常使用預設即可。但伺服器端程式執行緒功能不同時，建議命名。

#!/usr/bin/env python3
# coding=utf-8
import threading

def function(i):
  print ("function called by thread {0}".format(i))
threads = []

for i in range(5):
  t = threading.Thread(target=function , args=(i,))
  threads.append(t)
  t.start()
  t.join()

執行結果：

#

$ ./threading_define.py

function called by thread 0
function called by thread 1
function called by thread 2
function called by thread 3
function called by thread 4

##確定目前執行緒

#!/usr/bin/env python3
# coding=utf-8

import threading
import time

def first_function():
  print (threading.currentThread().getName()+ str(' is Starting \n'))
  time.sleep(3)
  print (threading.currentThread().getName()+ str( ' is Exiting \n'))
  
def second_function():
  print (threading.currentThread().getName()+ str(' is Starting \n'))
  time.sleep(2)
  print (threading.currentThread().getName()+ str( ' is Exiting \n'))
  
def third_function():
  print (threading.currentThread().getName()+\
  str(' is Starting \n'))
  time.sleep(1)
  print (threading.currentThread().getName()+ str( ' is Exiting \n'))
  
if __name__ == "__main__":
  t1 = threading.Thread(name='first_function', target=first_function)
  t2 = threading.Thread(name='second_function', target=second_function)
  t3 = threading.Thread(name='third_function',target=third_function)
  t1.start()
  t2.start()
  t3.start()

#執行結果：

$ ./threading_name.py

first_function is Starting 
second_function is Starting 
third_function is Starting 
third_function is Exiting 
second_function is Exiting 
first_function is Exiting

配合logging模組一起使用：

#!/usr/bin/env python3
# coding=utf-8

import logging
import threading
import time

logging.basicConfig(
  level=logging.DEBUG,
  format='[%(levelname)s] (%(threadName)-10s) %(message)s',
  )
  
def worker():
  logging.debug('Starting')
  time.sleep(2)
  logging.debug('Exiting')
  
def my_service():
  logging.debug('Starting')
  time.sleep(3)
  logging.debug('Exiting')
  
t = threading.Thread(name='my_service', target=my_service)
w = threading.Thread(name='worker', target=worker)
w2 = threading.Thread(target=worker) # use default name
w.start()
w2.start()
t.start()

執行結果：

$ ./threading_names_log.py[DEBUG] (worker  ) Starting

[DEBUG] (Thread-1 ) Starting
[DEBUG] (my_service) Starting
[DEBUG] (worker  ) Exiting
[DEBUG] (Thread-1 ) Exiting
[DEBUG] (my_service) Exiting

#在子類別中使用執行緒

前面我們的執行緒都是結構化程式設計的形式來創建。透過整合threading.Thread類別也可以創建線程。 Thread類別首先完成一些基本上初始化，然後呼叫它的run()。 run()方法會呼叫傳遞給建構函式的目標函式。

#!/usr/bin/env python3
# coding=utf-8

import logging
import threading
import time

exitFlag = 0

class myThread (threading.Thread):
  def __init__(self, threadID, name, counter):
    threading.Thread.__init__(self)
    self.threadID = threadID
    self.name = name
    self.counter = counter
    
  def run(self):
    print ("Starting " + self.name)
    print_time(self.name, self.counter, 5)
    print ("Exiting " + self.name)
    
def print_time(threadName, delay, counter):
  while counter:
    if exitFlag:
      thread.exit()
    time.sleep(delay)
    print ("%s: %s" %(threadName, time.ctime(time.time())))
    counter -= 1
    
# Create new threads
thread1 = myThread(1, "Thread-1", 1)
thread2 = myThread(2, "Thread-2", 2)
# Start new Threads
thread1.start()
thread2.start()
print ("Exiting Main Thread")

###執行結果：##########

$ ./threading_subclass.py

############

Starting Thread-1
Starting Thread-2
Exiting Main Thread
Thread-1: Tue Sep 15 11:03:21 2015
Thread-2: Tue Sep 15 11:03:22 2015
Thread-1: Tue Sep 15 11:03:22 2015
Thread-1: Tue Sep 15 11:03:23 2015
Thread-2: Tue Sep 15 11:03:24 2015
Thread-1: Tue Sep 15 11:03:24 2015
Thread-1: Tue Sep 15 11:03:25 2015
Exiting Thread-1
Thread-2: Tue Sep 15 11:03:26 2015
Thread-2: Tue Sep 15 11:03:28 2015
Thread-2: Tue Sep 15 11:03:30 2015
Exiting Thread-2

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