Hello,
I was wondering if anyone had any ideas
about https://github.com/golang/go/issues/21978 ("net/http: no Client API
to close server connection based on Response") -- it's an old issue, but
it's something that's biting me currently and I can't see a neat way to
solve it.
As an HTTP client, I'm hitting a case where some HTTP server instance
behind a load balancer breaks and starts returning 500s (FWIW with no body)
and without the "Connection: close" header. I retry, but I end up reusing
the same TCP connection to the same broken HTTP instance, so I never hit a
different backend server and my retry policy is basically useless.
Obviously I need to get the server owner to fix its behavior, but it would
be great if, as a client, there were a way to get net/http not to reuse the
connection further, in order to be less beholden to the server's behavior.
This happens with both HTTP/1.1 and HTTP/2.
If appropriate, I could live with the request to close the connection
racing with other new requests to the same endpoint. Getting to the point
where 2 or 3 requests fail and then the connection is closed is way better
than having requests fail ad infinitum.
http.Transport.CloseIdleConnections() doesn't solve the problem well (a)
because it's a big hammer, and (b) because there's no guarantee that the
connection is idle when CloseIdleConnections() is called.
FWIW I can see in `func (pc *persistConn) readLoop()` there's the following
test:
```go
if resp.Close || rc.req.Close || resp.StatusCode <= 199 || bodyWritable {
// Don't do keep-alive on error if either party requested a close
// or we get an unexpected informational (1xx) response.
// StatusCode 100 is already handled above.
alive = false
}
```
I imagine that extending that to `if resp.Close || rc.req.Close ||
resp.StatusCode <= 199 || bodyWritable || resp.StatusCode >= 500 {` might
probably help this specific case, but I imagine that's an unacceptably
large behavior change for the rest of the world.
I'm not sure how else this could be done. Does anyone have any thoughts?
Many thanks for the help,
Jim
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