python的标准库提供两个模块：thread和threading，thread是低级模块，threading是高级模块，对thread进行了封装
1 用threading模块创建多线程
- 第一种方法是把一个函数传入并创建Thread实例，然后调用start方法执行；
#!coding:utf-8
import random
import time,threading
#新线程执行的代码
def thread_run(urls):
print 'Current %s in running...' %threading.current_thread().name
for url in urls:
print '%s --->>> %s ' %(threading.current_thread().name,url)
time.sleep(random.random())
print('%s ended. '%threading.current_thread().name)
print('%s is running... ' %threading.current_thread().name)
t1 = threading.Thread(target=thread_run,name='Thread_1',args=(['url_1','url_2','url_3'],))
t2 = threading.Thread(target=thread_run,name='Thread_2',args=(['url_4','url_5','url_6'],))
t1.start()
t2.start()
t1.join()
t2.join()
print '%s ended.'% threading.current_thread().name
``` C:Python27python.exe F:/python_scrapy/python_study/Thread_test.py MainThread is running... Current Thread_1 in running... Thread_1 --->>> url_1 Current Thread_2 in running... Thread_2 --->>> url_4 Thread_1 --->>> url_2 Thread_2 --->>> url_5 Thread_1 --->>> url_3 Thread_1 ended. Thread_2 --->>> url_6 Thread_2 ended. MainThread ended.
Process finished with exit code 0
* 直接从threading.Thread继承并创建线程类，然后重写__init__方法和run方法
!coding:utf-8
import random,threading,time
class myThread(threading.Thread):
def init(self,name,urls):
threading.Thread.init(self,name=name)
self.urls=urls
def run(self):
print 'Current %s in running... '% threading.current_thread().name
for url in self.urls:
print '%s ---->>> %s' % (threading.current_thread().name,url)
time.sleep(random.random())
print '%s ended.' %threading.current_thread().name
print '%s is running... '%threading.current_thread().name
t1 = myThread(name='Thread_1',urls=['url_1','url_2','url_3'])
t2 = myThread(name='Thread_2',urls=['url_4','url_5','url_6'])
t1.start()
t2.start()
t1.join()
t2.join()
print '%s ended.'% threading.current_thread().name
* 运行结果：
C:Python27python.exe F:/python_scrapy/python_study/Threading.Thread_test.py
MainThread is running...
Current Thread_1 in running...
Thread_1 ---->>> url_1
Current Thread_2 in running...
Thread_2 ---->>> url_4
Thread_2 ---->>> url_5
Thread_1 ---->>> url_2
Thread_1 ---->>> url_3Thread_2 ---->>> url_6
Thread_2 ended.
Thread_1 ended.
MainThread ended.
Process finished with exit code 0