Better HTTP/1 connection reuse in Go 1.27
94 points by allddd 3 hours ago | 16 comments
rkuska 48 minutes ago
Now if you use json’s Decoder you can read a body and still might end up without reused connection - if a response contains a newline.
replyDecoder only reads X bytes (512? I don’t remember) and if the structure fits into these bytes exactly (and the multiplications of it) the newline leaves hanging there.
I always check for Decoder.More (this drains whitespace) after decoding.
nasretdinov 2 hours ago
It sucks that this changes the behaviour under the hood that you previously coukd rely on the fact that closing the response body lets you skip downloading the HTTP body entirely, but I do like the tradeoff here, since it also limits the download time to just 50ms you'd not get overwhelmed if your network can't keep up with all the cancelled HTTP bodies, you'll just wait a little bit of traffic instead.
replydonatj 37 minutes ago
> Using HTTP/1 (GODEBUG=http2client=0), calling this function 100 times against index.golang.org takes ~710 milliseconds on Go 1.26 on my machine. On Go 1.27, the same program takes ~150 milliseconds.
replyDoes this mean I need to disable http2 for this to work or is that just a further proof that http2 isn't actually being used?
giovannibajo1 30 minutes ago
As explained in the post, you don’t need any of this in HTTP/2, since you get the benefits of connection sharing without having to read the drain connection body by protocol design
replyMrDOS 22 minutes ago
Right. Although the article demonstrates the changes by making requests of a public web server, I would imagine this change has been primarily motivated by a desire to reduce overhead and latency on internal communication between microservices, which very often uses unencrypted HTTP/1 traffic.
replyjamesponddotco 2 hours ago
I can finally retire xhttp.DrainResponseBody[1], which I just learned, wasn’t doing that good of a job anyway.
reply[1]: https://github.com/cipherdothost/x-go/blob/caa562ded82b8c417...
aleksi 58 minutes ago
I can finally remove a similar helper that I copied from project to project and from company to company since r60
replyjamesponddotco 35 minutes ago
I built that package exactly to stop copying code from project to project.
replyNot because of the copy itself, since a little copy is better than a little dependency, as they say, but because it was a pain to update everything when I inevitably found a bug in what I copied.
prussian 2 hours ago
At the very end it mentions it won't drain bodies for Connection: close
Does this work with reverse proxies?
I've had issues with nginx still getting IO errors when my server doesn't consume bodies and bubbling them up as 5xx codes to the client.
I believe I've seen this with Firefox as well, where XHR status codes would be 0.
Early closing, without consuming body, seems to work as expected with Chrome and curl though.
reply
I can attest to the fact this is a Frequently Asked Question among people who are trying to Go as an HTTP client, so even though this feels somewhat icky, I can understand where it is coming from. However, I'm also missing, if I want to slam this connection closed, which is a reasonable thing to want, how do I do that without uselessly draining a socket I don't intend to reuse? Fake the "Connection: close" header into the Response object? Hope I can dig out an underlying socket of some sort under the concrete type of the Body.Response that I can bypass this code with? Seems like there should be a way to do that too.
> Note, however, that Transport will automatically try to read a Response Body to EOF asynchronously up to a conservative limit when a Body is closed.
Similar wording appears in a few other places; search for “asynchronously”.