为何非公平锁比公平锁效率高? - V2EX
kenduffy

为何非公平锁比公平锁效率高?

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  •   kenduffy Dec 1, 2017 5174 views
    This topic created in 3108 days ago, the information mentioned may be changed or developed.

    没懂逻辑

    只是后来的线程能抢占锁而已

    怎么效率就高了?

    6 replies    2017-12-01 22:53:21 +08:00
    sbw
        1
    sbw  
       Dec 1, 2017
    逻辑简单
    SoloCompany
        2
    SoloCompany  
       Dec 1, 2017 via iPhone
    这不是显然的吗
    现实中经济纠纷是私了效率高还是打官司效率高?
    hsiafan
        3
    hsiafan  
       Dec 1, 2017   1
    公平锁要维护一个队列,后来的线程要加锁,即使锁空闲,也要先检查有没有其他线程在 wait,如果有自己要挂起,加到队列后面,然后唤醒队列最前面的线程。这种情况下相比较非公平锁多了一次挂起和唤醒
    kenduffy
        4
    kenduffy  
    OP
       Dec 1, 2017
    @xiaxiaocao "然后唤醒队列最前面的线程"
    为何要唤醒最前面的线程?这个有啥意义?
    难道不是获得锁的正在执行的线程结束任务,释放锁的时候去唤醒最前面的线程么?
    lengyihan
        5
    lengyihan  
       Dec 1, 2017 via Android
    @SoloCompany 正解。
    lengyihan
        6
    lengyihan  
       Dec 1, 2017 via Android
    @SoloCompany 就跟上床一样,强奸肯定比谈恋爱快啊
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