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7.2.2.threading

  • 1.Introduction

    • This module constructs higher-level threading interfaces on top of the lower level threadarrow-up-right module. See also the mutex and Queue modules.

  • 2.Usage

    • 創建Thread的方式有兩種:

      • 1.創建一個類別並覆寫Threading.Thread:

        • 在此類別中的init()中傳入參數, 此參數通常是要讓thread執行的function, 呼叫super.init()

        • 覆寫run(), 通常在這裡執行傳入的function

      • 2.直接呼叫Threading.Thread

    • 比較好的架構如下:

      • -ThreadRunner-

        • 最上層的包裝, Thread的管理者:

          • 私有變數中有一個Thread pool, 可以是list或是dictionary

          • 提供addThreadWorker(), 以添加Thread(Worker)到Thread pool

          • 提供run(), 以啟動Thread pool中所有的Thread(Worker)

        class TheradRunner():
  def __init__(self):
      self.__threadPool = {}

  def addThreadWorker(self, worker, name):
      self.__threadPool.update({name:Thread(worker)})

  def run(self):
      for name, thread in self.__threadPool.items():
          thread.start()
      for name, thread in self.__threadPool.items():
          thread.join()

      • -Thread-

        • 繼承threading.Thread

          • 在init()中傳入Worker, 在這裡可以用hasattrarrow-up-right檢查woker的run()是否是callablearrow-up-right, 並用hasattr檢查worker的run是否存在

          • 在init()中呼叫super.init()

          • 覆寫run(), 通常在這裡執行傳入的function

        class Thread(threading.Thread):
  def __init__(self, workerClass):
      super().__init__()
      self.status = Status.Init
      if hasattr(workerClass, 'run') and callable(workerClass.run):
          self.__workerClass = workerClass
          self.exceptionMessage = None
      else:
          self.status = Status.Error
          self.exceptionMessage = 'Worker function error'

  def start(self):
      if Status.Init == self.status:
           self.status = Status.Running
           super().start()

 def run(self):
      try:
          self.__workerClass.run()
          self.status = Status.Success
      except Exception:
          self.exceptionMessage = traceback.format_exc()
          self.status = Status.Error

      • -Worker-

        • 提供run(), 真正要讓Thread作的事

        • 若有很多不同的事情分別要讓不同的thread執行, 則可以分別撰寫不同類別, 這些類別都需要繼承Worker

        class Worker():
  def run(self):
      pass
        class ReadLineWorker(Worker):
  def __init__(self, aHoldingZoneMap):
      self.__holdingZoneTableMap = aHoldingZoneMap

  def run(self):
      self.readLinesAndAttribute()

      • -製作新的thread-

        lineWorker = ReadLineWorker(holdingZoneTableMap)
threadRunner.addThreadWorker(lineWorker, 'ReadLineWorker')
threadRunner.run()

  • 3.Reference

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