import queue
import threading
class ThreadPool(object):
  def __init__(self, max_num=20):
    self.queue = queue.Queue(max_num) #創(chuàng)建隊(duì)列，最大數(shù)為20
    for i in range(max_num):
      self.queue.put(threading.Thread) #將類名放入隊(duì)列中
  def get_thread(self):
    return self.queue.get() #從隊(duì)列中取出類名
  def add_thread(self):
    self.queue.put(threading.Thread) #進(jìn)類名放入隊(duì)列中
def func(arg, p): #定義一個(gè)函數(shù)
  print(arg)
  import time
  time.sleep(2)
  p.add_thread()
pool = ThreadPool(10) #創(chuàng)建對(duì)象，并執(zhí)行該類的構(gòu)造方法，即將線程的類名放入隊(duì)列中
for i in range(30):
  thread = pool.get_thread() #調(diào)用該對(duì)象的get_thread方法，取出類名
  t = thread(target=func, args=(i, pool)) #創(chuàng)建對(duì)象，執(zhí)行func，參數(shù)在args中
  t.start()

import queue
import threading
import contextlib
import time
StopEvent = object()
class ThreadPool(object):
  def __init__(self, max_num, max_task_num = None):
    if max_task_num:
      self.q = queue.Queue(max_task_num)
    else:
      self.q = queue.Queue()
    self.max_num = max_num
    self.cancel = False
    self.terminal = False
    self.generate_list = []
    self.free_list = []
  def run(self, func, args, callback=None):
    """
    線程池執(zhí)行一個(gè)任務(wù)
    :param func: 任務(wù)函數(shù)
    :param args: 任務(wù)函數(shù)所需參數(shù)
    :param callback: 任務(wù)執(zhí)行失敗或成功后執(zhí)行的回調(diào)函數(shù)，回調(diào)函數(shù)有兩個(gè)參數(shù)1、任務(wù)函數(shù)執(zhí)行狀態(tài)；2、任務(wù)函數(shù)返回值（默認(rèn)為None，即：不執(zhí)行回調(diào)函數(shù)）
    :return: 如果線程池已經(jīng)終止，則返回True否則None
    """
    if self.cancel:
      return
    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):
    """
    創(chuàng)建一個(gè)線程
    """
    t = threading.Thread(target=self.call)
    t.start()
  def call(self):
    """
    循環(huán)去獲取任務(wù)函數(shù)并執(zhí)行任務(wù)函數(shù)
    """
    current_thread = threading.currentThread()
    self.generate_list.append(current_thread)
    event = self.q.get()
    while event != StopEvent:
      func, args, callback = event
      try:
        result = func(*args)
        success = True
      except Exception as e:
        success = False
        result = None
      if callback is not None:
        try:
          callback(success, result)
        except Exception as e:
          pass
      with self.worker_state(self.free_list, current_thread):
        if self.terminal:
          event = StopEvent
        else:
          event = self.q.get()
    else:
      self.generate_list.remove(current_thread)
  def close(self):
    """
    執(zhí)行完所有的任務(wù)后，所有線程停止
    """
    self.cancel = True
    count = len(self.generate_list)
    while count:
      self.q.put(StopEvent)
      count -= 1
  def terminate(self):
    """
    無論是否還有任務(wù)，終止線程
    """
    self.terminal = True
    while self.generate_list:
      self.q.put(StopEvent)
    self.q.queue.clear()
  @contextlib.contextmanager
  def worker_state(self, state_list, worker_thread):
    """
    用于記錄線程中正在等待的線程數(shù)
    """
    state_list.append(worker_thread)
    try:
      yield
    finally:
      state_list.remove(worker_thread)
# How to use
pool = ThreadPool(5)
def callback(status, result):
  # status, execute action status
  # result, execute action return value
  pass
def action(i):
  print(i)
for i in range(30):
  ret = pool.run(action, (i,), callback)
time.sleep(3)
print(len(pool.generate_list), len(pool.free_list))
print(len(pool.generate_list), len(pool.free_list))
pool.close()
# pool.terminate()