python多线程

单线程

# 单线程执行耗时
import logging
from time import sleep, ctime
​
logging.basicConfig(level=logging.INFO)
​
​
def loop0():
   logging.info("start loop at" + ctime())
   sleep(4)
   logging.info("end loop at" + ctime())
​
def loop1():
   logging.info("start loop0 at" + ctime())
   sleep(2)
   logging.info("end loop0 at" + ctime())
​
def main():
   logging.info("start all at" + ctime())
   loop0()
   loop1()
   logging.info("end all at" + ctime())
​
if __name__ == '__main__':
    main()

第一步 引入多线程_thread方法

# 调用_thread方法，进行优化，线程耗时缩短2s
# 但是实际项目执行中，sleep(6)未知(代码执行时间未知)，改方法存在缺陷
import _thread
import logging
from time import sleep, ctime
​
logging.basicConfig(level=logging.INFO)
​
​
def loop0():
   logging.info("start loop at" + ctime())
   sleep(4)
   logging.info("end loop at" + ctime())
​
def loop1():
   logging.info("start loop0 at" + ctime())
   sleep(2)
   logging.info("end loop0 at" + ctime())
​
def main():
   logging.info("start all at" + ctime())
   _thread.start_new_thread(loop0, ())
   _thread.start_new_thread(loop1, ())
   sleep(6)
   # loop0()
   # loop1()
   logging.info("end all at" + ctime())
​
if __name__ == '__main__':
    main()

第二步 多线程_thread方法引用lock

# _thread引用lock，进一步进行优化代码逻辑
# 但是lock概念比较复杂，代码简洁和易读性不佳
import _thread
import logging
from time import sleep, ctime
​
logging.basicConfig(level=logging.INFO)
​
loops=[2, 4]
def loop(nloop, nsec, lock):
   logging.info("start loop" + str(nloop) + "at" + ctime())
   sleep(nsec)
   logging.info("end loop" + str(nloop) + "at" + ctime())
   lock.release()
​
# def loop1():
#  logging.info("start loop0 at" + ctime())
#  sleep(2)
#  logging.info("end loop0 at" + ctime())
​
def main():
   logging.info("start all at" + ctime())
   # _thread.start_new_thread(loop0,())
   locks = []
   nloops = range(len(loops))
   for i in nloops:
      lock = _thread.allocate_lock()
      lock.acquire()
      locks.append(lock)
   for i in nloops:
      _thread.start_new_thread(loop, (i, loops[i], locks[i]))
   for i in nloops:
      while locks[i].locked():pass
   # _thread.start_new_thread(loop1, ())
   # sleep(6)
   # loop0()
   # loop1()
   logging.info("end all at" + ctime())
​
if __name__ == '__main__':
    main()

第三步 threading方法更加简洁

# threading方法执行多线程方法更加简洁了
# 把threading方法封装起来会不会更好？
import logging
import threading
from time import sleep, ctime
​
logging.basicConfig(level=logging.INFO)
​
loops=[2, 4]
​
def loop(nloop, nsec):
   logging.info("start loop " + str(nloop) + " at" + ctime())
   sleep(nsec)
   logging.info("end loop " + str(nloop) + " at" + ctime())
​
def main():
   logging.info("start all at" + ctime())
   threads =[]
   nloops = range(len(loops))
   for i in nloops:
      t = threading.Thread(target=loop, args=(i, loops[i]))
      threads.append(t)
   for i in nloops:
      threads[i].start()
   for i in nloops:
      threads[i].join()
   logging.info("end all at" + ctime())
​
if __name__ == '__main__':
    main()

第四步 封装threading方法、重写run方法

# 单线程程序执行耗时,threading方法执行多线程
# 把threading方法封装起来，重写run方法，使得代码更加清晰易读
import logging
import threading
from time import sleep, ctime
​
logging.basicConfig(level=logging.INFO)
​
loops=[2, 4]
​
class MyThread(threading.Thread):
   def __init__(self, func, args, name=''):
      threading.Thread.__init__(self)
      self.func = func
      self.args = args
      self.name = name
​
   def run(self):
      self.func(*self.args)
​
def loop(nloop, nsec):
   logging.info("start loop " + str(nloop) + " at" + ctime())
   sleep(nsec)
   logging.info("end loop " + str(nloop) + " at" + ctime())
​
def main():
   logging.info("start all at" + ctime())
   threads =[]
   nloops = range(len(loops))
   for i in nloops:
      t = MyThread(loop, (i, loops[i]), loop.__name__)
      threads.append(t)
   for i in nloops:
      threads[i].start()
   for i in nloops:
      threads[i].join()
   logging.info("end all at" + ctime())
​
if __name__ == '__main__':
    main()