7.2.2.threading

• 1.Introduction

  • This module constructs higher-level threading interfaces on top of the lower level thread 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hasattr檢查woker的run()是否是callable, 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

  • https://docs.python.org/2/library/threading.html

  • http://sebastiandahlgren.se/2014/06/27/running-a-method-as-a-background-thread-in-python/

  • https://puremonkey2010.blogspot.tw/2012/07/python-python-threading.html