OS_chapter4.3_thread_190420

OS_chapter4.3_thread

4.3.1 concept of thread(线程)

leading question

• program : draw circle & square at same time (ppt)
• first DrawCircle() then DrawRect()
• by order not the same

conclusion

• process can’t concurrence(并发) actually
• thread

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Thread

• create thread

• Windows : CreateThread()
  

  • ThreadFunction 作为函数指针指向原型函数

• 改进程序 : 将DrawCircle() ,DrawRect() 作为参数传递给CreateThread() 而非 直接调用

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单线程/多线程(single-thread / multi-thread)

4.3.2 typical status of thread

1. 程序的多个功能需要并发运行

• EG: video online concurrence functions: 1. 视频解码 2.音频解码 3. 网络接收
• nitiate a thread for each function to realize their concurrence

2. 改善窗口交互性(线程实现后台并发运行)(ppt)
3. 改善程序结构(将function以线程封装组织程序)
4. 多核CPU应用,充分发挥多核性能

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supplement

• afxBeginThread()是CreateThread()的一个封装(简单于CreateThread)
• remote将thread封装在第三方进程空间中
• Linux
  
  

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the shortcomings of thread

1. 程序难以调试(非顺序执行)
2. 并发过程难以控制(互斥访问等)
3. 线程安全问题