线程池：

方案简介：

方案一：简单版本的线程池，每次都要创建线程池；

方案二：支持传函数、传参、传回调函数、立即终止所有线程、最大优点：线程的循环利用，节省时间和资源  ★★★★★

方案三：现有模块，直接调用即可，不支持回调函数

方案一：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import Queue
import threading
 
 
class ThreadPool(object):
 
    def __init__(self, max_num=20):
        self.queue = Queue.Queue(max_num)
        for i in xrange(max_num):
            self.queue.put(threading.Thread)
 
    def get_thread(self):
        return self.queue.get()
 
    def add_thread(self):
        self.queue.put(threading.Thread)
 
"""
pool = ThreadPool(10)
 
def func(arg, p):
    print arg
    import time
    time.sleep(2)
    p.add_thread()
 
 
for i in xrange(30):
    thread = pool.get_thread()
    t = thread(target=func, args=(i, pool))
    t.start()
"""

　方案二：

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import queue
import threading
import contextlib
import time

StopEvent = object()

class ThreadPool(object):

    def __init__(self, max_num):
        self.q = queue.Queue()
        self.max_num = max_num

        self.terminal = False
        self.generate_list = []
        self.free_list = []

    def run(self, func, args, callback=None):
        """
        线程池执行一个任务
        :param func: 任务函数
        :param args: 任务函数所需参数
        :param callback: 任务执行失败或成功后执行的回调函数，回调函数有两个参数1、任务函数执行状态；2、任务函数返回值（默认为None，即：不执行回调函数）
        :return: 如果线程池已经终止，则返回True否则None
        """

        if len(self.free_list) == 0 and len(self.generate_list) < self.max_num:
            self.generate_thread()
        w = (func, args, callback,)
        self.q.put(w)

    def generate_thread(self):
        """
        创建一个线程
        """
        t = threading.Thread(target=self.call)
        t.start()

    def call(self):
        """
        循环去获取任务函数并执行任务函数
        """
        current_thread = threading.currentThread
        self.generate_list.append(current_thread)

        event = self.q.get()
        while event != StopEvent:

            func, arguments, callback = event
            try:
                result = func(*arguments)
                status = True
            except Exception as e:
                status = False
                result = e

            if callback is not None:
                try:
                    callback(status, result)
                except Exception as e:
                    pass

            if self.terminal: # False
                event = StopEvent
            else:
                with self.worker_state(self.free_list,current_thread):
                    event = self.q.get()

        else:
            self.generate_list.remove(current_thread)

    @contextlib.contextmanager
    def worker_state(self,x,v):
        x.append(v)
        try:
            yield
        finally:
            x.remove(v)

    def close(self):
        num = len(self.generate_list)
        while num:
            self.q.put(StopEvent)
            num -= 1

    # 终止线程（清空队列）
    def terminate(self):

        self.terminal = True

        while self.generate_list:
            self.q.put(StopEvent)
        self.q.empty()

import time

def work(i):
    time.sleep(1)
    print(i)

pool = ThreadPool(10)
for item in range(50):
    pool.run(func=work, args=(item,))

# pool.terminate() #立即终止所有线程

方案三、

from concurrent.futures import ThreadPoolExecutor
import time

def f1(a):
    time.sleep(2)
    print(a)
    return 1

pool=ThreadPoolExecutor(5)
for i in range(30):
    a=pool.submit(f1,i)
    # x=a.result()#获取返回值,如果有，会阻塞