问题描述
我可以在不需要锁的情况下在多线程程序中使用映射或哈希映射吗?即它们是线程安全的吗?
Can I use a map or hashmap in a multithreaded program without needing a lock?i.e. are they thread safe?
我想同时在地图中添加和删除.
I'm wanting to potentially add and delete from the map at the same time.
似乎有很多相互矛盾的信息.
There seems to be a lot of conflicting information out there.
顺便说一下，我在 Ubuntu 10.04 下使用 GCC 自带的 STL 库
By the way, I'm using the STL library that comes with GCC under Ubuntu 10.04
就像互联网上的其他人一样，我似乎得到了相互矛盾的答案?
Just like the rest of the internet, I seem to be getting conflicting answers?
推荐答案
您可以安全地执行同步读取操作，即调用 const 成员函数.但是，如果其中一个涉及编写，则不能同时执行任何操作，即非常量成员函数的调用对于容器应该是唯一的，并且不能与任何其他调用混合使用.
You can safely perform simultaneous read operations, i.e. call const member functions. But you can't do any simultaneous operations if one of then involves writing, i.e. call of non-const member functions should be unique for the container and can't be mixed with any other calls.
即您不能从多个线程更改容器.所以你需要使用lock/rw-lock以确保访问安全.
i.e. you can't change the container from multiple threads. So you need to use lock/rw-lockto make the access safe.
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