处理有条件的未消费 http.IncomingMessage

Question

我想通过 restify 服务器将上游 http.IncomingMessage 转发给客户端。这就是我到目前为止的想法。它提供转发能力。但是我认为这可能会导致内存泄漏：

var server = restify.createServer()

server.get('/test', function(req, res, next) {
    var upstreamReq = createUpstreamReq() // just creates a http.ClientRequest

    upstreamReq.on('response', function(upstreamRes) {
        if (upstreamRes.statusCode === 404) {
            // (1) I guess this leaks the upstreamRes body ?
            return next(new restify.errors.NotFoundError())
        }
        if (upstreamRes.statusCode !== 200) {
            // (2) is there a better way than pipeing the response to /dev/null?
            // I guess the advantage of this approach is that we can reuse the connection (not closed) ?
            upstreamRes.pipe(fs.createWriteStream('/dev/null'))
            return next(new restify.errors.InternalServerError())
        }
        res.setHeader('Content-Type', upstreamRes.header('Content-Type'))
        res.setHeader('Content-Length', upstreamRes.header('Content-Length'))
        upstreamRes.pipe(res)
        return next()
    })

    upstreamReq.end()
})

我假设在上游 404 的情况下，此代码会泄漏 upstreamRes 主体 (1)，因为它从未被消耗（没有 pipe(somewhere)）？
一个不应该泄漏 upstreamRes 主体的明显解决方案 (2) 是将其通过管道传输到 /dev/null。这个问题有 alternative/better 解决方案吗？

Answer 1

我似乎跳过了文档中关于 http.ClientRequest 的一个重要部分：

If no 'response' handler is added, then the response will be entirely discarded. However, if you add a 'response' event handler, then you must consume the data from the response object, either by calling response.read() whenever there is a 'readable' event, or by adding a 'data' handler, or by calling the .resume() method. Until the data is consumed, the 'end' event will not fire. Also, until the data is read it will consume memory that can eventually lead to a 'process out of memory' error.

https://nodejs.org/api/http.html#http_class_http_clientrequest

所以正确答案似乎是：

您需要为每个 http.ClientRequest

http.IncomingMessage

如果您对返回的数据不感兴趣，建议的方法是调用 upstreamRes.resume()。即使没有附加消费者，这也会启动数据流。

处理有条件的未消费 http.IncomingMessage

Handling of conditionally unconsumed http.IncomingMessage

node.js

restify

node-streams