线程2
一，守护线程
守护线程和守护进程是一样的，都是随着主进程或者主线程的结束而结束
from threading import Thread import time def func(): print('22') time.sleep(1) print('22') t= Thread(target=func) t.setDaemon(True) t.start()
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py 22 Process finished with exit code 0
当我们再起一个线程时：
from threading import Thread import time def func(): print('11') time.sleep(1) print('22') t= Thread(target=func) t.setDaemon(True) t.start() t1= Thread(target=func) t1.start()
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py 11 11 22 22 Process finished with exit code 0
二，线程的锁
from threading import Thread from threading import Lock import time def func(): global n time.sleep(1) # l.acquire() n-=1 # l.release() n=10 l=Lock() l1=[] for i in range(10): t=Thread(target=func) t.start() l1.append(t) [t.join() for t in l1] print(n)
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py
0
Process finished with exit code 0
有种特殊情况：
from threading import Thread from threading import Lock import time def func(): global n time.sleep(1) # l.acquire() tt=n #从进程中获取值 time.sleep(1) n=tt-1 #再返回进程 # l.release() n=10 l=Lock() l1=[] for i in range(10): t=Thread(target=func) t.start() l1.append(t) [t.join() for t in l1] print(n)
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py 9 Process finished with exit code 0
这种情况还是要加锁的：
from threading import Thread from threading import Lock import time def func(): global n time.sleep(1) l.acquire() tt=n time.sleep(1) n=tt-1 l.release() n=10 l=Lock() l1=[] for i in range(10): t=Thread(target=func) t.start() l1.append(t) [t.join() for t in l1] print(n)
GIL锁的不是数据，而是线程
三，死锁
from threading import RLock from threading import Thread from threading import Lock import time a=Lock() b=Lock() def kill(name): a.acquire() print('%s拿到枪了'%name) b.acquire() print('%s拿到子弹了'%name) print('%s杀人了' % name) b.release() a.release() def kill1(name): b.acquire() print('%s拿到子弹了' % name) time.sleep(1) a.acquire() print('%s拿到枪了' % name) print('%s杀人了' % name) a.release() b.release() Thread(target=kill,args=('二狗',)).start() Thread(target=kill1,args=('大狗',)).start() Thread(target=kill,args=('三狗',)).start() Thread(target=kill1,args=('四狗',)).start()
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py
二狗拿到枪了
二狗拿到子弹了
二狗杀人了
大狗拿到子弹了
三狗拿到枪了
这就是死锁现象了，怎么解决这个问题呢？
from threading import RLock from threading import Thread from threading import Lock import time b=a=RLock() def kill(name): a.acquire() print('%s拿到枪了'%name) b.acquire() print('%s拿到子弹了'%name) print('%s杀人了' % name) b.release() a.release() def kill1(name): b.acquire() print('%s拿到子弹了' % name) time.sleep(1) a.acquire() print('%s拿到枪了' % name) print('%s杀人了' % name) a.release() b.release() Thread(target=kill,args=('二狗',)).start() Thread(target=kill1,args=('大狗',)).start() Thread(target=kill,args=('三狗',)).start() Thread(target=kill1,args=('四狗',)).start()
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py
二狗拿到枪了
二狗拿到子弹了
二狗杀人了
大狗拿到子弹了
大狗拿到枪了
大狗杀人了
三狗拿到枪了
三狗拿到子弹了
三狗杀人了
四狗拿到子弹了
四狗拿到枪了
四狗杀人了
Process finished with exit code 0
用RLock就可以解决这个问题了
lock是互斥锁
RLock是递归锁
四 信号量
from threading import Thread from threading import Semaphore import time import random def func(i,sem): sem.acquire() print('我是%s'%i) time.sleep(random.random()) print('我是%s'%i) sem=Semaphore(5) for i in range(10): Thread(target=func,args=(i,sem)).start()
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py
我是0
我是1
我是2
我是3
我是4
我是3
我是4
我是1
我是2
我是0
信号量和线程池的区别，信号量是一次就显示这些线程，而线程池是每次就开这么多线程
五，事件
from threading import Event from threading import Thread from threading import Semaphore import time import random def func(): count = 1 while not e.is_set(): # 当事件的flag为False时才执行循环内的语句 if count > 3: raise TimeoutError print('尝试连接第%s次' % count) count += 1 e.wait(0.5) # 一直阻塞变成了只阻塞0.5 print('连接成功') # 收到check_conn函数内的set指令，让flag变为True跳出while循环,执行本句代码 def check_conn(): ''' 检测数据库服务器的连接是否正常 ''' time.sleep(random.randint(1, 2)) # 模拟连接检测的时间 e.set() # 告诉事件的标志数据库可以连接 e = Event() check = Thread(target=check_conn) check.start() conn = Thread(target=func) conn.start()
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py
尝试连接第1次
尝试连接第2次
连接成功
Process finished with exit code 0
六，，条件
import threading def func(i): t.acquire() t.wait() print('hello%s'%i) t.release() if __name__=='__main__': t=threading.Condition()#条件，锁加wait（）功能 for i in range(10): threading.Thread(target=func,args=(i,)).start() while 1: info=input('>>>') if info=='q': break t.acquire() if info=='all': t.notify_all() else: t.notify(int(info)) t.release()
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py >>>2 >>>hello0 hello1
根据你设定的条件，设定每次执行多少线程
七，定时器
from threading import Timer def func(): print('hello') Timer(4,func).start()
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py
hello
Process finished with exit code 0
八，队列
import queue t=queue.LifoQueue() t.put(1) t.put(2) t.put(3) print(t.get()) C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py 3 Process finished with exit code 0
后进先出
import queue t=queue.PriorityQueue() t.put((1,'q')) t.put((4,'e')) t.put((3,'g')) t.put((3,'o')) print(t.get()) print(t.get()) print(t.get()) print(t.get())
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py (1, 'q') (3, 'g') (3, 'o') (4, 'e') Process finished with exit code 0
# 值越小越优先,值相同就asc码小的先出
九，concurrent
import time import random from concurrent import futures def func(n): print(n) time.sleep(random.randint(1,3)) return n*'*' def fu(c): print(c.result()) f=futures.ThreadPoolExecutor(3)#线程池 f.submit(func,2)#submit=start
C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py 2 Process finished with exit code 0
返回值：
import time import random from concurrent import futures def func(n): print(n) time.sleep(random.randint(1,3)) return n*'*' def fu(c): print(c.result()) f=futures.ThreadPoolExecutor(3)#线程池 t=f.submit(func,2)#submit=start print(t.result())#result打印返回值 C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py 2 ** Process finished with exit code 0
import time import random from concurrent import futures def func(n): print(n) time.sleep(random.randint(1,3)) return n*'*' def fu(c): print(c.result()) f=futures.ThreadPoolExecutor(3)#线程池 l=[] for i in range(10): t=f.submit(func,i)#submit=start l.append(t) f.shutdown()#相当于close()和join()集合体 for i in l: print(i.result()) C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py 0 1 2 3 4 5 6 7 8 9 * ** *** **** ***** ****** ******* ******** ********* Process finished with exit code 0
回调：
import time import random from concurrent import futures def func(n): # print(n) time.sleep(random.randint(1,3)) return n*'*' def fu(c): print(c.result()) f=futures.ThreadPoolExecutor(3)#线程池 l=[] for i in range(10): # t=f.submit(func,i)#submit=start # l.append(t) # f.shutdown()#相当于close()和join()集合体 # for i in l: # print(i.result()) f.submit(func,i).add_done_callback(fu)#回调 C:\Users\hc\AppData\Local\Programs\Python\Python36\python3.exe C:/s9/day39/39.py ** * ***** *** **** ****** ******** ********* ******* Process finished with exit code 0
