Nginx Patch: SPDY/3.1 protocol implementation
mailman.nginx.org
mailman.nginx.org
> Three companies that like Google's approach -- Automattic, MaxCDN, and CloudFlare -- are funding Nginx developers to update its SPDY support to version 3.1, CNET has learned. Under the deal, SPDY 3.1 should arrive in Nginx 1.5 in January, a source familiar with the partnership said.
http://news.cnet.com/8301-1023_3-57616193-93/nginx-upgrade-f...
I don't think this is a problem given that the patch is being openly pushed into the "public" source immediately. It'd also be extremely challenging to pay "the community" for a patch like this (how do you divvy up the funds? per SLOC?), although technically you could always directly pay a single contributor or two.
Directly engaging Nginx Inc seems to be both the surest way to get something delivered and avoid a lot of PR risk, if you ask me.
Server push is one of the spec items that got much wanted clarifications in SPDY3 and would be awesome to see nginx support that. Apache mod_spdy, jetty and netty do have it.
Server push makes it handy to provide super low latencies for full page loading by pushing out all the files that "server thinks" browser might need for a page without waiting for the requests.
Server push is not a magic bullet, it can take more bandwidth compared to the regular visit with a browser that has required resources (images, css, js etc) cached. But still better than inlining in html because the resources from server push can be cached.
If you care more about page loading speed (especially for first-time visitors) and less about actual bandwidth consumed, SPDY with server push can be great. Hint: deciding on whether visitor might benefit from "a little push" as a fresh visitor could be done with a cookie existence check or smth similar.
Even if it were to show an improvement in some situations (different round trip times or network speeds), it would be in the microseconds to couple of milliseconds range; with a large variance.
Given that it degrades performance for second-time visitors, I would recommend not enabling it without further benchmarking.
a) Page A currently inlines half dozen small assets on every page. These inlined resources inflate every page and are delivered at same priority as HTML. By contrast, a "dumb push" server delivers these same assets as individual resources via push. Net benefit? Basically same performance since inlining is a form of application-layer push. However, a smart server can at least prioritize and multiplex push bytes in a smarter way... Now, let's make the server just a tiny bit smarter. If it's the same TCP connection and the server has already pushed the resource, don't push it on next request. Now we're also saving bytes... <insert own smarter strategy here>.
b) Page B has two CSS and one JS file in the critical rendering path. Without push you either inline all three (ouch), or, you roundtrip to the client and get it to parse the HTML to discover these resources and come back to the server... With push, the server can avoid the extra RTT and push those assets directly to the client -- this is a huge performance win. How does the server know? Well, either you made it smart.. or you use some adaptive strategy like looking at past referrers and building a map of "when client requests X, they also come back for Y and Z" - this is already available in Jetty.
The fears of extra bytes are also somewhat exaggerated (they're valid, but exaggerated). The client, if they desire, can disable push. The client can also use flow-control to throttle how much data can be transferred in first push window (both FF and Chrome do this already). Lastly, the client can always decline and/or RST a push resource.
Some additional resources: - http://chimera.labs.oreilly.com/books/1230000000545/ch12.htm... - http://www.igvita.com/2013/06/12/innovating-with-http-2.0-se...
I am no longer with the company for whom I performed the benchmarks, that's why I can't publish them. Perhaps there are other benchmarks out there, that show server push is more performant. If so, I would be happy to see them.
Jetty guys had a couple of nice demos they showed off at various conferences. Here's one: http://www.youtube.com/watch?v=4Ai_rrhM8gA
make -f objs/Makefile
make[1]: Entering directory `/home/newman314/src/nginx-1.5.9'
cc -c -pipe -O -W -Wall -Wpointer-arith -Wno-unused-parameter -Werror -g -march=native -Ofast -fomit-frame-pointer -fstack-protector -D_FORTIFY_SOURCE=2 -I src/core -I src/event -I src/event/modules -I src/os/unix -I objs \
-o objs/src/core/ngx_string.o \
src/core/ngx_string.c
{standard input}: Assembler messages:
{standard input}:1253: Error: no such instruction: `vfmadd312sd .LC5(%rip),%xmm1,%xmm0'
make[1]: *** [objs/src/core/ngx_string.o] Error 1
src/http/ngx_http_request.c: In function ‘ngx_http_set_virtual_server’:
src/http/ngx_http_request.c:1955:32: error: ‘cscf’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
cc1: all warnings being treated as errors
Are you using a new CPU with an old(er) gcc version? Try specifying -march explicitly instead of native.
This is with gcc 4.6.3.
I hope that nginx will maintain spdy2 and serve version 3 to compatible clients. My company just upgraded to Firefox 14...
If they need to better manage Firefox updates, I recommend they look at swapping to Firefox ESR (Extended Support Release). See https://www.mozilla.org/en-US/firefox/organizations/ for more information.
SPDY 2, that is. SPDY 3 will still be supported.
So HTTP 1.1 lasted for 20 years without significant changes, but SPDY which has been around for a year or so and is already on version 3, with extra point-releases for shit and giggles.
If you're going to create a protocol and want it to be used internet-wide can you at least plan up front and keep things stable once released?
Glad I don't have to maintain and deploy any code related to this. Jesus christ.
This is why I like date-based version numbering, such as Ubuntu 13.10 or C++11.
All those changes to, say, 802.11n, WebSockets or OAuth2? Drafts too.