如何在node.js中编写线程安全代码 [英] How to write thread safe code in node.js

问题描述

这是我的app.js的一部分：

Here's a part of my app.js:

var connections = [];

function removeConnection(res) {
    var i = connections.indexOf(res);
    if (i !== -1) {
        connections.splice(i, 1);
    }
}

我在请求关闭时调用removeConnection：

And I call removeConnection when a request is closed:

req.on('close', function () {
    console.log("connection closed");
    removeConnection(res);
});

我想知道上面的代码是否是线程安全的？我的意思是Node.js是事件驱动的，可能是以下场景？

I wonder if the above code is thread safe? I mean as Node.js is event driven, is the following scenario possible?

1. connections是[a，b，c]


2. threadB调用removeConnection


3. 在threadB.removeConnection中：i = 1


4. threadA调用removeConnection
$ b threadA.removeConnection中的$ b
5. ：i = 0


6. ：threadA.removeConnection：connections.splice（0,1）; => connections是[b，c]


7. 在threadA.removeConnection中：connections.splice（1,1）; => connections是[b]

1. connections is [a,b,c]
2. threadB calls removeConnection
3. in threadB.removeConnection: i = 1
4. threadA calls removeConnection
5. in threadA.removeConnection: i = 0
6. in threadA.removeConnection: connections.splice(0, 1); => connections is [b,c]
7. in threadA.removeConnection: connections.splice(1, 1); => connections is [b]

正如您在此场景中看到的那样，将删除threadC的连接而不是threadB的连接。

As you see in this scenario, threadC's connection would be removed instead of threadB's.

这可能发生吗？如果是，那么我应该如何修复代码？

Can this happen? If yes, then how should I fix the code?

推荐答案

Node.js的一个关键原则是所有用户代码在单个线程中运行，这使开发人员无需处理编写线程安全代码的复杂性。

One of the key principles of Node.js is that all user code runs in a single thread which eliminates the need for the developer to deal with the complexities of writing thread-safe code.

所以你的代码（以及所有Node.js代码）根据定义是线程安全的。

So your code (and all Node.js code) is by definition thread-safe.

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