golang body.close 的默认行为？

前提是复用 http 链接，采用 stream 读法。

采用 stream 读法并不读完这个链接的 body，比如整个请求是 1M，只读了 1k，这时候 close，会发生什么？

是会读完完整的 1M 再放回到 http 复用池中还是读 tcp 缓冲区的大小？因为从 golang net/http/transfer.go 中看是读了 maxPostHandlerReadBytes 的长度。但是自己理解不了，缓冲区读完后服务端因为滑动窗口不是会继续发送之前阻塞的数据吗，这样又不是可用状态了。

maxPostHandlerReadBytes is the max number of Request.Body bytes not consumed by a handler that the server will read from the client in order to keep a connection alive. If there are more bytes than this then the server to be paranoid instead sends a "Connection: close" response.

This number is approximately what a typical machine's TCP buffer size is anyway. (if we have the bytes on the machine, we might as well read them)

上面这段话该如何理解呢？