Oh, sorry, I read that as GODEBUG=http2debug=1. Okay, I'll follow up in https://golang.org/issues/16582
On Tue, Aug 2, 2016 at 7:00 PM, Russ Amos <r...@google.com> wrote: > Those messages aren't GODEBUG output, it's the errors printed by the > program as received from http.Client.Get. I'll file a bug. > > On Tue, Aug 2, 2016 at 9:51 PM Brad Fitzpatrick <bradf...@golang.org> > wrote: > >> Sorry, I don't read all of golang-nuts@ and never saw that. You could've >> escalated, though. There are at least two bug trackers available to you: >> >> http://b/ >> https://github.com/golang/go/issues (the one I prefer) >> >> But I think your interpretation of the the HTTP/2 client is wrong. >> >> If you're a video person, there's a talk on Go's HTTP client and its >> HTTP/2<->HTTP/1<->HTTP/2 dialing sandwich... >> https://www.youtube.com/watch?v=FARQMJndUn0 >> If you're not a video person, the slides are linked from youtube. >> >> Your output in this email from your program ( >> https://play.golang.org/p/zKthX7Y9RW) doesn't include any error output. >> You can ignore the GODEBUG output. If it says there's no cached connection, >> that means http2 has no cached connection it needs to dial (which http1 >> will do). Then http1 works as normal, unless it decides that it negotiated >> http2, and then it goes back to http2. >> >> But any rate-limiting you refer to is unchanged from before, since HTTP/1 >> still dials as normal. There's an open bug to optimize it (to only start 1 >> or 2 TCP connections until we know the negotiated protocol, and then settle >> on 6 or 1 max connections, etc), but it's no different today than Go 1.5 >> and earlier. >> >> In any case, if you have a reproducible bug, let's move this to a bug >> tracker. >> >> >> >> >> >> >> >> >> >> >> >> >> On Tue, Aug 2, 2016 at 6:36 PM, 'Russ Amos' via golang-nuts < >> golang-nuts@googlegroups.com> wrote: >> >>> I'm seeing "http2: no cached connection was available" failures from >>> http.Client when I start many (~hundreds) requests at once. (This issue was >>> also posted to golang-nuts@ in April >>> <https://groups.google.com/d/topic/golang-nuts/0YEWYwBOJPI/discussion>, >>> with no response) >>> >>> I may not understand correctly, but I thought this kind of usage was >>> fine with HTTP 1.1 and net/http, because the spec mandates a max number of >>> outgoing connections to any given host, so http.Client throttles open >>> connections and effectively queues requests past that. The http2 package >>> seems not to do the same. That might be correct according to the spec (I >>> don't know), but makes using http.Client weird -- I need to rate limit its >>> usage if the server is HTTP 2, but it does rate limiting for me if the >>> server is HTTP 1.1. >>> >>> Is my understanding correct? Is this a bug? Is the expectation that my >>> app should be rate limiting, regardless of server version? >>> >>> Also, It seems the error being returned is exported >>> <https://godoc.org/golang.org/x/net/http2#pkg-variables> in the http2 >>> package, but is not exported in the bundled version >>> <https://golang.org/src/net/http/h2_bundle.go#L4775> in net/http. If it >>> was exported, I think I could at least retry on my own, but perhaps that's >>> not the intended usage anyway. >>> >>> I wrote this program <https://play.golang.org/p/zKthX7Y9RW> hitting >>> https://www.google.com/ to demonstrate -- here are a few run results: >>> >>> $ GODEBUG=http2client=0 go run /tmp/foo.go >>> $ GODEBUG=http2client=0 go run /tmp/foo.go >>> $ GODEBUG=http2client=0 go run /tmp/foo.go >>> $ GODEBUG=http2client=0 go run /tmp/foo.go >>> $ GODEBUG=http2client=0 go run /tmp/foo.go >>> >>> $ GODEBUG=http2client=1 go run /tmp/foo.go >>> Get https://www.google.com/: http2: no cached connection was available >>> Get https://www.google.com/: http2: no cached connection was available >>> Get https://www.google.com/: http2: no cached connection was available >>> ... >>> $ GODEBUG=http2client=1 go run /tmp/foo.go >>> Get https://www.google.com/: http2: no cached connection was available >>> $ GODEBUG=http2client=1 go run /tmp/foo.go >>> $ GODEBUG=http2client=1 go run /tmp/foo.go >>> Get https://www.google.com/: http2: no cached connection was available >>> Get https://www.google.com/: http2: no cached connection was available >>> Get https://www.google.com/: http2: no cached connection was available >>> ... >>> $ GODEBUG=http2client=1 go run /tmp/foo.go >>> Get https://www.google.com/: http2: no cached connection was available >>> Get https://www.google.com/: http2: no cached connection was available >>> Get https://www.google.com/: http2: no cached connection was available >>> ... >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "golang-nuts" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to golang-nuts+unsubscr...@googlegroups.com. >>> For more options, visit https://groups.google.com/d/optout. >>> >> -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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