From: Shawn Pearce <firstname.lastname@example.org>
To: Ilari Liusvaara <email@example.com>
Cc: ForceCharlie <firstname.lastname@example.org>, git <email@example.com>
Subject: Re: Git Smart HTTP with HTTP/2.0
Date: Sat, 11 Jul 2015 10:23:09 -0700 [thread overview]
Message-ID: <CAJo=hJs21m1C6+rdvCid311-TapK=QKLkqrH8aUZmzHH7CpVug@mail.gmail.com> (raw)
On Sat, Jul 11, 2015 at 12:00 AM, Ilari Liusvaara
> On Sat, Jul 11, 2015 at 11:10:48AM +0800, ForceCharlie wrote:
>> As we known, HTTP/2.0 has been released. All Git-Smart-HTTP are currently
>> implemented using HTTP/1.1.
> Nit: It is HTTP/2.
>> Frequently used Git developers often feel Git HTTP protocol is not
>> satisfactory, slow and unstable.This is because the HTTP protocol itself
> Note that there are already two versions of HTTP transport, the old "dumb"
> one and the newer "smart" one.
> The smart one is difficult to speed up (due to nature of the negotiations),
> but usually is pretty reliable (the efficiency isn't horrible).
The negotiation in smart-HTTP actually has some bad corner cases. Each
round of negotiation requires a new POST resupplying all previously
agreed upon SHA-1s, and a batch of new SHA-1s. We have observed many
rounds where this POST is MiBs in size because the peers can't quite
agree and have to keep digging through history.
The native protocol on git:// and SSH is not as bad. Negotiation is
still many rounds, but these are pipelined and each round does not
need to repeat the prior round, as the server has a single stream and
is saving state.
> Now, the old "dumb" protocol is pretty unreliable and slow. HTTP/2 probably
> can't do anything with the reliability problems, but probably could improve
> the speed a bit.
> Websockets over HTTP/2 (a.k.a. "websockets2") has not been defined yet.
> With Websockets(1), it would probably already be possible to tunnel the
> native git smart transport protocol over it. Probably not worth it.
Another option is to tunnel using gRPC (grpc.io). libcurl probably
can't do this. And linking grpc.io library into git-core is crazy. So
its probably a non-starter. But food for thought.
But, at $DAY_JOB we tunnel the native bidirectional protocol in
grpc.io's predecessor, and it works quite well for us.
next prev parent reply other threads:[~2015-07-11 17:23 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-11 3:10 Git Smart HTTP with HTTP/2.0 ForceCharlie
2015-07-11 7:00 ` Ilari Liusvaara
2015-07-11 17:23 ` Shawn Pearce [this message]
2015-07-11 18:26 ` Ilari Liusvaara
2015-07-11 23:10 ` Shawn Pearce
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