C ++ 11 STL容器和线程安全 [英] C++11 STL containers and thread safety

问题描述

我无法找到关于此的任何最新信息。

Do C ++ 11版本的STL容器有一定程度的线程安全性？ / p>

我预期他们不会，由于性能原因。但是，再次，这就是为什么我们有 vector :: operator [] 和 vector :: at 。

解决方案

由于现有的答案不覆盖它（只有一个注释），我只提到23.2.2 [container.requirements .dataraces]的当前 C ++标准规范，其中说：

向量 除了之外的不同元素中包含的对象的内容是相同的序列时，需要使用

实现来避免数据竞争同时修改。

ie它可以安全地访问同一个容器的不同元素，例如你可以有一个全局 std :: vector< std :: future< int>> 有十个线程，每个写入向量的不同元素。

除此之外，相同的规则适用于容器和其余的标准库（见17.6 .5.9 [res.on.data.races]），因为 Mr.C64的回答说，另外[container.requirements .dataraces]列出了一些可以安全调用的非const成员函数，因为它们只返回对元素的非const引用，它们实际上不修改任何东西（通常任何非const成员函数必须被认为是修改。 ）

I have trouble finding any up-to-date information on this.

Do C++11 versions of STL containers have some level of thread safety guaranteed?

I do expect that they don't, due to performance reasons. But than again, that's why we have both vector::operator [] and vector::at.

解决方案

Since the existing answers don't cover it (only a comment does), I'll just mention 23.2.2 [container.requirements.dataraces] of the current C++ standard specification which says:

implementations are required to avoid data races when the contents of the contained object in different elements in the same sequence, excepting vector<bool>, are modified concurrently.

i.e. it's safe to access distinct elements of the same container, so for example you can have a global std::vector<std::future<int>> of ten elements and have ten threads which each write to a different element of the vector.

Apart from that, the same rules apply to containers as for the rest of the standard library (see 17.6.5.9 [res.on.data.races]), as Mr.C64's answer says, and additionally [container.requirements.dataraces] lists some non-const member functions of containers that can be called safely because they only return non-const references to elements, they don't actually modify anything (in general any non-const member function must be considered a modification.)

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