python 多线程
一、参考出处
参考链接：https://docs.python.org/3/library/threading.html#module-threading
二、threading模块介绍
1）threading模块通过 Thread 创建线程
方式一：
#方式一 from threading import Thread import time def sayhi(name): time.sleep(2) print('%s say hello' %name) if __name__ == '__main__': t=Thread(target=sayhi,args=('egon',)) t.start() print('主线程')
方式二：
#方式二 from threading import Thread import time class Sayhi(Thread): def __init__(self,name): super().__init__() self.name=name def run(self): time.sleep(2) print('%s say hello' % self.name) if __name__ == '__main__': t = Sayhi('egon') t.start() print('主线程')
2）threading/ Thread方法介绍：
Thread实例对象的方法 isAlive(): 返回线程是否活动的。 getName(): 返回线程名。 setName(): 设置线程名。
threading模块提供的一些方法： threading.currentThread(): 返回当前的线程变量。 threading.enumerate(): 返回一个包含正在运行的线程的list。正在运行指线程启动后、结束前，不包括启动前和终止后的线程。 threading.activeCount(): 返回正在运行的线程数量，与 len(threading.enumerate())有相同的结果。 threading.RLock(*args, **kwargs): 线程递归锁
threading.Condition() 条件变量
threading.Semaphore()
hreading.BoundedSemaphore()
threading.Event()
3）Thread 方法举例
from threading import Thread import threading from multiprocessing import Process import os def work(): import time time.sleep(3) print(threading.current_thread().getName()) if __name__ == '__main__': #在主进程下开启线程 t=Thread(target=work) t.start() print(threading.current_thread().getName()) print(threading.current_thread()) #主线程 print(threading.enumerate()) #连同主线程在内有两个运行的线程 print(threading.active_count()) print('主线程/主进程') ''' 打印结果: MainThread <_MainThread(MainThread, started 140735268892672)> [<_MainThread(MainThread, started 140735268892672)>, <Thread(Thread-1, started 123145307557888)>] 主线程/主进程 Thread-1 '''
4）threading模块介绍
RLock：
def RLock(*args, **kwargs): """Factory function that returns a new reentrant lock. A reentrant lock must be released by the thread that acquired it. Once a thread has acquired a reentrant lock, the same thread may acquire it again without blocking; the thread must release it once for each time it has acquired it. """ if _CRLock is None: return _PyRLock(*args, **kwargs) return _CRLock(*args, **kwargs)
样例： 同一线程中 可以多次申请锁。不同作用域中 应使用 同一个 RLock 创建的锁 多个 不同 RLock 锁 还是会造成死锁
from threading import Thread,Lock import time mutexB = mutexA=RLock() class MyThread(Thread): def run(self): self.func1() self.func2() def func1(self): mutexA.acquire() print('\033[41m%s 拿到A锁\033[0m' %self.name) mutexB.acquire() print('\033[42m%s 拿到B锁\033[0m' %self.name) mutexB.release() mutexA.release() def func2(self): mutexB.acquire() print('\033[43m%s 拿到B锁\033[0m' %self.name) time.sleep(2) mutexA.acquire() print('\033[44m%s 拿到A锁\033[0m' %self.name) mutexA.release() mutexB.release() if __name__ == '__main__': for i in range(10): t=MyThread() t.start() ''' Thread-1 拿到A锁 Thread-1 拿到B锁 Thread-1 拿到B锁 Thread-2 拿到A锁 然后就卡住，死锁了 '''
Lock：
Lock = _allocate_lock _allocate_lock = _thread.allocate_lock def allocate_lock(): # real signature unknown; restored from __doc__ """ allocate_lock() -> lock object (allocate() is an obsolete synonym) Create a new lock object. See help(type(threading.Lock())) for information about locks. """ pass
样例： Lock 造成死锁。
from threading import Thread,Lock import time mutexA=Lock() mutexB=Lock() class MyThread(Thread): def run(self): self.f1() self.f2() def f1(self): mutexA.acquire() print('%s 拿到了A锁' %self.name) mutexB.acquire() print('%s 拿到了B锁' %self.name) mutexB.release() mutexA.release() def f2(self): mutexB.acquire() print('%s 拿到了B锁' % self.name) time.sleep(0.1) mutexA.acquire() print('%s 拿到了A锁' % self.name) mutexA.release() mutexB.release() if __name__ == '__main__': for i in range(10): t=MyThread() t.start()
Semaphore：
def acquire(self, blocking=True, timeout=None): def release(self):
样例：
from threading import Thread,Semaphore,currentThread import time,random sm=Semaphore(3) def task(): # sm.acquire() # print('%s in' %currentThread().getName()) # sm.release() with sm: print('%s in' %currentThread().getName()) time.sleep(random.randint(1,3)) if __name__ == '__main__': for i in range(10): t=Thread(target=task) t.start()
Event：
def is_set(self): """Return true if and only if the internal flag is true.""" return self._flag def set(self): """Set the internal flag to true.”“” def clear(self): """Reset the internal flag to false.”“” def wait(self, timeout=None): """Block until the internal flag is true”“”
样例：
from threading import Thread,Event,currentThread import time event=Event() def conn(): n=0 while not event.is_set(): if n == 3: print('%s try too many times' %currentThread().getName()) return print('%s try %s' %(currentThread().getName(),n)) event.wait(0.5) n+=1 print('%s is connected' %currentThread().getName()) def check(): print('%s is checking' %currentThread().getName()) time.sleep(5) event.set() if __name__ == '__main__': for i in range(3): t=Thread(target=conn) t.start() t=Thread(target=check) t.start()
Condition：
class Condition: def wait(self, timeout=None): 调用这个方法将使线程进入Condition的等待池等待通知，并释放锁。使用前线程必须已获得锁定，否则将抛出异常。 pass def wait_for(self, predicate, timeout=None): pass def notify(self, n=1) 调用这个方法将从等待池挑选一个线程并通知，收到通知的线程将自动调用acquire()尝试获得锁定（进入锁定池）；其他线程仍然在等待池中。调用这个方法不会释放锁定。使用前线程必须已获得锁定，否则将抛出异常。 pass def notify_all(self): 调用这个方法将通知等待池中所有的线程，这些线程都将进入锁定池尝试获得锁定。调用这个方法不会释放锁定。使用前线程必须已获得锁定，否则将抛出异常。 pass def acquire(self, *args): 调用关联的锁的相应方法 pass def release(self): 调用关联的锁的相应方法 pass
样例：
#coding=utf-8 __author__ = 'Bruce_Zhou' import threading import time import datetime num = 0 con = threading.Condition() class Gov(threading.Thread): def __init__(self): super(Gov, self).__init__() def run(self): global num con.acquire() while True: print "开始拉升股市" num += 1 print "拉升了" + str(num) + "个点" time.sleep(2) if num == 5: print "暂时安全！" con.notify() con.wait() con.release() class Consumers(threading.Thread): def __init__(self): super(Consumers, self).__init__() def run(self): global num con.acquire() while True: if num > 0: print "开始打压股市" num -= 1 print "打压了" + str(num) + "个点" time.sleep(2) if num == 0: print "你妹的！天台在哪里！" con.notify() con.wait() con.release() if __name__ == '__main__': p = Gov() c = Consumers() p.start() c.start()
Timer
class Timer(Thread): def cancel(self): """Stop the timer if it hasn't finished yet.""" self.finished.set() def run(self): self.finished.wait(self.interval) if not self.finished.is_set(): self.function(*self.args, **self.kwargs) self.finished.set()
样例：
from threading import Timer import random import sys class Code: def __init__(self): self.make_cache() def make_cache(self,interval=5): self.cache=self.make_code() print(self.cache) self.t=Timer(interval,self.make_cache) self.t.start() def make_code(self,n=4): res='' for i in range(n): s1=str(random.randint(0,9)) s2=chr(random.randint(65,90)) res+=random.choice([s1,s2]) return res def check(self): while True: code=input('请输入你的验证码>>: ').strip() if code.upper() == self.cache: print('验证码输入正确') self.t.cancel() break obj=Code() obj.check()
concurrent.futures：进程线程池
ThreadPoolExecutor和ProcessPoolExecutor两个类，实现了对threading和multiprocessing的进一步抽象，对编写线程池/进程池提供了直接的支持。
参考：https://www.cnblogs.com/kangoroo/p/7628092.html
参考：https://www.cnblogs.com/dylan-wu/p/7163823.html
样例：
from concurrent.futures import ThreadPoolExecutor, Executor import requests import time def get(url): print('GET %s' %url) response=requests.get(url) time.sleep(3) return {'url':url,'content':response.text} def parse(res): res=res.result() print('%s parse res is %s' %(res['url'],len(res['content']))) if __name__ == '__main__': urls=[ 'http://www.cnblogs.com/linhaifeng', 'https://www.python.org', 'https://www.openstack.org', ] pool=ThreadPoolExecutor(2) for url in urls: pool.submit(get,url).add_done_callback(parse)
