多线程复习 Rlock ,Condition,Semaphore

#对于io操作来说，多线程和多进程性能差别不大
#1.通过Thread类实例化

import time
import threading

def get_detail_html(url):
    print("get detail html started")
    time.sleep(2)
    print("get detail html end")


def get_detail_url(url):
    print("get detail url started")
    time.sleep(4)
    print("get detail url end")


#2. 通过集成Thread来实现多线程


class GetDetailHtml(threading.Thread):
    def __init__(self, name):
        super().__init__(name=name)

    def run(self):
        print("get detail html started")
        time.sleep(2)
        print("get detail html end")


class GetDetailUrl(threading.Thread):
    def __init__(self, name):
        super().__init__(name=name)

    def run(self):
        print("get detail url started")
        time.sleep(4)
        print("get detail url end")

if  __name__ == "__main__":
    thread1 = GetDetailHtml("get_detail_html")
    thread2 = GetDetailUrl("get_detail_url")
    start_time = time.time()
    thread1.start()
    thread2.start()

    thread1.join()
    thread2.join()

    #当主线程退出的时候， 子线程kill掉
    print ("last time: {}".format(time.time()-start_time))

线程间通信 -Queue

#通过queue的方式进行线程间同步
from queue import Queue


import time
import threading


def get_detail_html(queue):
    #爬取文章详情页
    while True:
        url = queue.get()
        # for url in detail_url_list:
        print("get detail html started")
        time.sleep(2)
        print("get detail html end")


def get_detail_url(queue):
    # 爬取文章列表页
    while True:
        print("get detail url started")
        time.sleep(4)
        for i in range(20):
            queue.put("http://projectsedu.com/{id}".format(id=i))
        print("get detail url end")


#1. 线程通信方式- 共享变量

if  __name__ == "__main__":
    detail_url_queue = Queue(maxsize=1000)


    thread_detail_url = threading.Thread(target=get_detail_url, args=(detail_url_queue,))
    for i in range(10):
        html_thread = threading.Thread(target=get_detail_html, args=(detail_url_queue,))
        html_thread.start()
    # # thread2 = GetDetailUrl("get_detail_url")
    start_time = time.time()
    # thread_detail_url.start()
    # thread_detail_url1.start()
    #
    # thread1.join()
    # thread2.join()
    detail_url_queue.task_done()
    detail_url_queue.join()

    #当主线程退出的时候， 子线程kill掉
    print ("last time: {}".format(time.time()-start_time))

 线程锁，lock和Rlock

from threading import Lock, RLock, Condition #可重入的锁

#在同一个线程里面，可以连续调用多次acquire， 一定要注意acquire的次数要和release的次数相等
total = 0
lock = RLock()
def add():
    #1. dosomething1
    #2. io操作
    # 1. dosomething3
    global lock
    global total
    for i in range(1000000):
        lock.acquire()
        lock.acquire()
        total += 1
        lock.release()
        lock.release()


def desc():
    global total
    global lock
    for i in range(1000000):
        lock.acquire()
        total -= 1
        lock.release()
        

import threading
thread1 = threading.Thread(target=add)
thread2 = threading.Thread(target=desc)
thread1.start()
thread2.start()


#
thread1.join()
thread2.join()
print(total)

#1. 用锁会影响性能
#2. 锁会引起死锁
#死锁的情况 A（a，b）
"""
A(a、b)
acquire (a)
acquire (b)

B(a、b)
acquire (a)
acquire (b)
"""

 条件变量-线程间同步

import threading

#条件变量， 用于复杂的线程间同步
# class XiaoAi(threading.Thread):
#     def __init__(self, lock):
#         super().__init__(name="小爱")
#         self.lock = lock
#
#     def run(self):
#         self.lock.acquire()
#         print("{} : 在 ".format(self.name))
#         self.lock.release()
#
#         self.lock.acquire()
#         print("{} : 好啊 ".format(self.name))
#         self.lock.release()
#
# class TianMao(threading.Thread):
#     def __init__(self, lock):
#         super().__init__(name="天猫精灵")
#         self.lock = lock
#
#     def run(self):
#
#         self.lock.acquire()
#         print("{} : 小爱同学 ".format(self.name))
#         self.lock.release()
#
#         self.lock.acquire()
#         print("{} : 我们来对古诗吧 ".format(self.name))
#         self.lock.release()

#通过condition完成协同读诗

class XiaoAi(threading.Thread):
    def __init__(self, cond):
        super().__init__(name="小爱")
        self.cond = cond

    def run(self):
        with self.cond:
            self.cond.wait()
            print("{} : 在 ".format(self.name))
            self.cond.notify()

            self.cond.wait()
            print("{} : 好啊 ".format(self.name))
            self.cond.notify()

            self.cond.wait()
            print("{} : 君住长江尾 ".format(self.name))
            self.cond.notify()

            self.cond.wait()
            print("{} : 共饮长江水 ".format(self.name))
            self.cond.notify()

            self.cond.wait()
            print("{} : 此恨何时已 ".format(self.name))
            self.cond.notify()

            self.cond.wait()
            print("{} : 定不负相思意 ".format(self.name))
            self.cond.notify()

class TianMao(threading.Thread):
    def __init__(self, cond):
        super().__init__(name="天猫精灵")
        self.cond = cond

    def run(self):
        with self.cond:
            print("{} : 小爱同学 ".format(self.name))
            self.cond.notify()
            self.cond.wait()

            print("{} : 我们来对古诗吧 ".format(self.name))
            self.cond.notify()
            self.cond.wait()

            print("{} : 我住长江头 ".format(self.name))
            self.cond.notify()
            self.cond.wait()

            print("{} : 日日思君不见君 ".format(self.name))
            self.cond.notify()
            self.cond.wait()

            print("{} : 此水几时休 ".format(self.name))
            self.cond.notify()
            self.cond.wait()

            print("{} : 只愿君心似我心 ".format(self.name))
            self.cond.notify()
            self.cond.wait()



if __name__ == "__main__":
    from concurrent import futures
    cond = threading.Condition()
    xiaoai = XiaoAi(cond)
    tianmao = TianMao(cond)

    #启动顺序很重要
    #在调用with cond之后才能调用wait或者notify方法
    #condition有两层锁， 一把底层锁会在线程调用了wait方法的时候释放， 上面的锁会在每次调用wait的时候分配一把并放入到cond的等待队列中，等到notify方法的唤醒
    xiaoai.start()
    tianmao.start()

Semaphore 是用于控制进入数量的锁

#Semaphore 是用于控制进入数量的锁
#文件， 读、写， 写一般只是用于一个线程写，读可以允许有多个

#做爬虫
import threading
import time

class HtmlSpider(threading.Thread):
    def __init__(self, url, sem):
        super().__init__()
        self.url = url
        self.sem = sem

    def run(self):
        time.sleep(2)
        print("got html text success")
        self.sem.release()

class UrlProducer(threading.Thread):
    def __init__(self, sem):
        super().__init__()
        self.sem = sem

    def run(self):
        for i in range(20):
            self.sem.acquire()
            html_thread = HtmlSpider("https://baidu.com/{}".format(i), self.sem)
            html_thread.start()

if __name__ == "__main__":
    sem = threading.Semaphore(3)
    url_producer = UrlProducer(sem)
    url_producer.start()

 

转载于:https://www.cnblogs.com/Erick-L/p/8915199.html