Thanks for the extremely quick triage, Brad. I'll work around it in my program, for now.
On Tue, Aug 2, 2016 at 10:08 PM Brad Fitzpatrick <bradf...@golang.org> wrote: > 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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