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dinghao188
V2EX    C++

关于 memory_order_relaxed

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  •   dinghao188 2021-03-05 20:40:26 +08:00 1280 次点击
    这是一个创建于 1748 天前的主题,其中的信息可能已经有所发展或是发生改变。

    今天看到 atomic 相关的东西,然后就顺到了关于 memory_order 的东西

    网上说下面的代码有可能会出现 r1 == 1111 && r2 == 1111 的情况,我运行了几万遍了,还是没碰到。还是说只是理论上会出现?大佬们怎么看?

    #include <iostream> #include <thread&g; #include <atomic> using namespace std; atomic_int x {0}; atomic_int y {1}; void func1() { int r1 = y.load(std::__1::memory_order_relaxed); x.store(r1, std::__1::memory_order_relaxed); } void func2() { int r2 = x.load(std::__1::memory_order_relaxed); y.store(1111, std::__1::memory_order_relaxed); } int main() { thread t1(func1); thread t2(func2); t1.join(); t2.join(); } 
    codehz
        1
    codehz  
       2021-03-05 20:45:18 +08:00
    在 apple silicon 上就有效果了,intel 强制严格内存序
    dinghao188
        2
    dinghao188  
    OP
       2021-03-08 14:40:01 +08:00
    @codehz 原来是这样,改天试下
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