python线程threading处理任务并发一

python用多线程处理任务并发情况。thread生命周期：1、创建对象时，代表 Thread 内部被初始化。2、调用 start() 方法后，thread 会开始运行。

3、thread 代码正常运行结束或者是遇到异常，线程会终止。函数表达式：threading.Thread(group=None, target=None, name=None, args=(), kwargs={}, *, daemon=None)

直接创建thread,传递callable(可调用）对象。从输出可以看出，两个任务同时执行。

import threading
import time

def test():

    for i in range(5):
        print('test ',i,time.ctime())
        time.sleep(1)


thread = threading.Thread(target=test)
thread.start()


for i in range(5):
    print("main",i,time.ctime())
    time.sleep(1)

"""output"""

test main  00 Sun Oct 25 15:07:05 2020 
Sun Oct 25 15:07:05 2020
test main  11  Sun Oct 25 15:07:06 2020Sun Oct 25 15:07:06 2020

test main  22 Sun Oct 25 15:07:07 2020 
Sun Oct 25 15:07:07 2020
test main  33  Sun Oct 25 15:07:08 2020Sun Oct 25 15:07:08 2020

test main  44  Sun Oct 25 15:07:09 2020
Sun Oct 25 15:07:09 2020

 thread.current_thread() .name返回线程名字

import threading
import time

def test():

    for i in range(5):
        print(threading.current_thread().name+"test",i,time.ctime())
        time.sleep(1)


thread = threading.Thread(target=test,name="testthread")
thread.start()

for i in range(5):
    print(threading.current_thread().name+"main",i,time.ctime())
    time.sleep(1)

"""output"""

testthreadtestMainThreadmain  00  Sun Oct 25 15:35:55 2020Sun Oct 25 15:35:55 2020

MainThreadmaintestthreadtest  11  Sun Oct 25 15:35:56 2020Sun Oct 25 15:35:56 2020

MainThreadmaintestthreadtest 2 2 Sun Oct 25 15:35:57 2020 
Sun Oct 25 15:35:57 2020
MainThreadmain testthreadtest 33  Sun Oct 25 15:35:58 2020Sun Oct 25 15:35:58 2020

testthreadtestMainThreadmain  44  Sun Oct 25 15:35:59 2020Sun Oct 25 15:35:59 2020

 Thread 的 is_alive() 方法查询线程是否还在运行。is_alive() 返回 True 的情况是 Thread 对象被正常初始化，start() 方法被调用，

然后线程的代码还在正常运行。join()提供线程阻赛手段，让一个线程先运行，一个后运行。默认的情况是，join() 会一直等待对应线程的结束，

但可以通过参数赋值，等待规定的时间就好了:join(timeout=None)

import threading
import time

def test():

    for i in range(5):
        print(threading.current_thread().name+"test",i,time.ctime())
        time.sleep(0.5)


thread = threading.Thread(target=test,name="testthread")
thread.start()
thread.join()


for i in range(5):
    print(threading.current_thread().name+"main",i,time.ctime())
    print(thread.name + "is alive", thread.is_alive())
    time.sleep(1)

"""output"""

testthreadtest 0 Sun Oct 25 16:15:08 2020
testthreadtest 1 Sun Oct 25 16:15:09 2020
testthreadtest 2 Sun Oct 25 16:15:09 2020
testthreadtest 3 Sun Oct 25 16:15:10 2020
testthreadtest 4 Sun Oct 25 16:15:10 2020
MainThreadmain 0 Sun Oct 25 16:15:11 2020
testthreadis alive False
MainThreadmain 1 Sun Oct 25 16:15:12 2020
testthreadis alive False
MainThreadmain 2 Sun Oct 25 16:15:13 2020
testthreadis alive False
MainThreadmain 3 Sun Oct 25 16:15:14 2020
testthreadis alive False
MainThreadmain 4 Sun Oct 25 16:15:15 2020
testthreadis alive False

thread中的 daemon 属性。Thread 的构造方法中有一个 daemon 参数，默认是 None。如果要达到，MainThread 结束，子线程也立马结束，怎么做呢？

可以在子线程的构造器中传递 daemon 的值为 True。 thread = threading.Thread(target=test,name='TestThread',daemon=True)

面向对象编程实现以上线程代码：自定义一个 Thread 的子类，然后复写它的 run() 方法

import threading
import time

class TestThread(threading.Thread):

    def __init__(self, name=None):

        threading.Thread.__init__(self,name=name)

    def run(self):
        for i in range(5):
            print(threading.current_thread().name + "test",i)
            time.sleep(1)


thread = TestThread(name="testthread")
thread.start()

for i in range(5):
    print(threading.current_thread().name + "main",i)
    print(thread.name + "is alive", thread.is_alive())
    time.sleep(1)

睡眠排序法

import threading
from time import sleep,ctime

lst=[1,3,2,4]

def f(n):
    sleep(n)
    print(n,threading.current_thread().name,ctime())

threads=[]
for i in range(len(lst)):
    thread = threading.Thread(target=f,args=(lst[i]))
    threads.append(thread)

for i in range(len(lst)):
    threads[i].start()

"""OUTPUT"""

1 Thread-1 Sun Oct 25 22:40:57 2020
2 Thread-3 Sun Oct 25 22:40:58 2020
3 Thread-2 Sun Oct 25 22:40:59 2020
4 Thread-4 Sun Oct 25 22:41:00 2020

import threading

class MyThreading(threading.Thread):
    def __init__(self, func, arg):
        super(MyThreading, self).__init__()
        self.func = func
        self.arg = arg
    # 重写run()方法
    def run(self):
        self.func(self.arg)


def my_func(args):
    '''
    此处可以把你想让线程做的事定义在这里
    '''
    print("我是业务函数...")
    pass
obj = MyThreading(my_func, 123)
obj.start()

import threading
from time import sleep,ctime

class Mythread(threading.Thread):
    def __init__(self, func, args):
        threading.Thread.__init__(self)
        self.func = func
        self.args = args

    #重写run()方法
    def run(self):
        self.func(self.args)
        

lst = [2,4,3,5]

def my_func(n):
    sleep(n)
    print(n,threading.current_thread().name,ctime())


threads=[]
for i in range(len(lst)):
    thread = Mythread(my_func,args=(lst[i]))
    threads.append(thread)

for i in range(len(lst)):
    threads[i].start()