FastCGI binding or implementation? (page 2)

On 2011-10-18 19:24, Jeremy Sandell wrote: > On Mon, Oct 17, 2011 at 2:11 PM, Jacob Carlborg <doob@me.com > <mailto:doob@me.com>> wrote: > > On 2011-10-17 16:01, Andrea Fontana wrote: > > I handle request on different threads. I do some pre-processing on > scgi data and I fill a struct: > > request.get[] > request.post[] > request.cookie[] > request.headers[string] > > then I call a virtual function (to override on subclasses) like: > > do(request, output); > > where user fill output struct in a way like: > > output.data ~= "<html><body><h1>hello world</h1></body></html>"; > output.status = 200 > output.cookies = bla bla > > and then if is method != "head" i send headers + data, else just > "headers". > > btw 99% of usage is get, post, head. > > > Yes, but if you want to write a web site that is RESTful you need > the other HTTP methods as well, at least PUT and DELETE. > > BTW, what about creating something like Rack but for D. Rack is a > low level interface in front of the web server which web frameworks > can be built on top. > > http://rack.github.com/ > > -- > /Jacob Carlborg > > > Yes, this is exactly why I was wondering whether FastCGI had been > implemented (though SCGI works for me as well) - so that I could write > something on top of it, in much the same way I would using (for example) > WSGI in Python. > > I also agree with you re: supporting all of the HTTP methods. Just > because the most common ones are GET, POST, and HEAD doesn't mean we > should leave out the others; both PUT and DELETE are quite useful. > > Best regards, > Jeremy Sandell Although I have no idea if the rest of the 9 HTTP methods are useful, e.g. trace, options, connect and patch. -- /Jacob Carlborg

October 19, 2011

Re: FastCGI binding or implementation?

Posted by Jacob Carlborg
in reply to Adam D. Ruppe

Permalink

Jacob Carlborg

Posted in reply to Adam D. Ruppe

Permalink

On 2011-10-18 20:21, Adam D. Ruppe wrote:
> Tale time, only tangentially on topic.
>
>
> Today, I was coincidentally switching one of my work apps from
> standard CGI to Fast CGI.
>
> Almost trivial. Set up Apache, then build the program with
> -version=fastcgi. Done.
>
> Well, not 100% done. I had a piece of static data in the app
> that worked correctly before but now means subsequent requests
> were out of it.
>
> Changed that to an instance variable, and boom, works perfectly.
>
>
> * If you are using Fast CGI, avoid static variables.
>
>
>
> The next thing is speed. From principles, there's very little
> reason for FastCGI to actually be faster than normal CGI - the
> startup costs are insignificant next to the total app runtime
> and network lag. (Startup is maybe 5 ms on the live server,
> with runtime close to 50ms and ping to the user another 100ms.
> The "cost" of CGI is roundoff error in the actual deployment.)
>
>
> My benchmarks supported this for the kind of loads we had before.
>
>
> But now, the number of concurrent users is picking up. The CGI
> still performed very well, though every so often, users complained
> about lag on some resources.
>
> I ran a benchmark comparing cgi to fast cgi with a very large
> number of concurrent users.
>
> It showed better availability and about a 15% speed boost under
> this load. Since Apache restarts it when it segfaults, reliability
> ought not to be affected, though it's too soon to say for sure.
>
>
> So, I changed the makefile to say "-version=fastcgi" and soon
> realized I must search for static variables - found just one,
> so easy fix, and we're up on fastcgi.
>
>
> ... but that 15% in the benchmark hasn't translated to a big change
> in the live environment yet. Been several hours now, and we've
> been trying to force the availability issue, and failed so far.
>
> Looks like a win, but not a very big one. Speed on the whole -
> unaffected. The difference is roundoff error once you factor in
> network lag and such again.
>
>
>
> So, how can we speed up the application? The key here is client
> side caching.
>
> Using my cgi.d, there's a function:
>
> cgi.setCache(true);
>
> which tells it simply to cache the response forever. It makes
> an expiration date long in the future.
>
> Set that for any content which changes infrequently - css,
> javascript, images, any kind of (conceptually) pure or static data,
> etc.
>
> Now, your code doesn't run again and the user doesn't hit the
> network again. What was 150ms is now<  1ms. The users will feel
> the difference.
>
> You might set even data that changes often to cache for a few
> minutes. Odds are the user doesn't need it to revalidate on the
> server every minute. cgi.d's setResponseExpires can help here,
> just set it a little bit in the future.
>
> If the user hits a link to go back to a page then, it will
> load from cache most the time, making navigating the site feel
> snappy. Until the time expires, then it's wait again, but IMO
> some cache is better than none.
>
> Remember: you can cache AJAX responses too.
>
>
>
>
> What if the resource actually does change? You'll want to change
> the link. When compiling, there's a __TIMESTAMP__ special token.
> A quick and dirty method is to use that __TIMESTAMP__ on your
> resource URLs in your html so every time you recompile, it
> invalidates the user's cache.
>
> <script src="/myapp/functions.js?{$timestamp}"></script>
>
>
>
> A better way might be to hash the content at compile time, but
> I haven't written code that can do this well enough for real
> work yet.

Yeah, that's how Rails 3.1 does it now. Rails 3.1 inserts a hash of the content in the file name instead of a time stamp after the question mark.

> * Caching makes a much bigger difference than just about any other
>    technique. You'll still want fast code for the cold cache users,
>    but as they browse your site, a good cache policy can shave
>    full seconds off the experience.
>
>    The fastest code is running no code at all.

Why not just cache the generated HTML and let Apache handle it. Then it doesn't even need to start the application if the cache is available.

-- 
/Jacob Carlborg

AFAIK other http methods have nothing special. You have just to implement on your code: if (request.method == "PUT") { ... ... } if you need them. Am i wrong? Il giorno mer, 19/10/2011 alle 08.36 +0200, Jacob Carlborg ha scritto: > On 2011-10-18 19:24, Jeremy Sandell wrote: > > On Mon, Oct 17, 2011 at 2:11 PM, Jacob Carlborg <doob@me.com <mailto:doob@me.com>> wrote: > > > > On 2011-10-17 16:01, Andrea Fontana wrote: > > > > I handle request on different threads. I do some pre-processing on > > scgi data and I fill a struct: > > > > request.get[] > > request.post[] > > request.cookie[] > > request.headers[string] > > > > then I call a virtual function (to override on subclasses) like: > > > > do(request, output); > > > > where user fill output struct in a way like: > > > > output.data ~= "<html><body><h1>hello world</h1></body></html>"; > > output.status = 200 > > output.cookies = bla bla > > > > and then if is method != "head" i send headers + data, else just > > "headers". > > > > btw 99% of usage is get, post, head. > > > > > > Yes, but if you want to write a web site that is RESTful you need > > the other HTTP methods as well, at least PUT and DELETE. > > > > BTW, what about creating something like Rack but for D. Rack is a > > low level interface in front of the web server which web frameworks > > can be built on top. > > > > http://rack.github.com/ > > > > -- > > /Jacob Carlborg > > > > > > Yes, this is exactly why I was wondering whether FastCGI had been implemented (though SCGI works for me as well) - so that I could write something on top of it, in much the same way I would using (for example) WSGI in Python. > > > > I also agree with you re: supporting all of the HTTP methods. Just because the most common ones are GET, POST, and HEAD doesn't mean we should leave out the others; both PUT and DELETE are quite useful. > > > > Best regards, > > Jeremy Sandell > > Although I have no idea if the rest of the 9 HTTP methods are useful, e.g. trace, options, connect and patch. >

Andrea Fontana: > other http methods have nothing special Indeed. The only thing that might get you is if the data's content type is different than the default. That's possible on POST too, though, so still nothing special. My cgi library has an enum to tell you what the requestMethod is, and it lists all the options in the standard. It, however, does not handle all possible content-types. It does x-www-form-urlencoded and multipart/form-data, so it can handle virtually all web forms out there - including file uploads - but if you want others, it'll take a minor modification. The best way to do it is probably to not attempt to parse it in the library at all, and just pass a range of raw data to the application.

Jacob Carlborg: > Why not just cache the generated HTML and let Apache handle it. That sounds hard... configuring Apache to do anything beyond the most trivial of tasks is a huge pain to me. It is easy to call "cgi.setCache(true);" though. > Then it doesn't even need to start the application if the cache is available. It's better with a client side cache. If it's available, you don't have to go to the server at all! Server side caching is something I haven't done yet; it's never been useful to me.

On 2011-10-19 16:36, Adam Ruppe wrote: > Jacob Carlborg: >> Why not just cache the generated HTML and let Apache handle it. > > That sounds hard... configuring Apache to do anything beyond the most > trivial of tasks is a huge pain to me. No, it's not that hard. Just add a couple of rewrite-rules that checks if a request matches an already cached page and rewrite it to the cached page. Something like this: </VirtualHost *:80> ... RailsAllowModRewrite On RewriteEngine On RewriteCond %{THE_REQUEST} ^(GET|HEAD) RewriteCond %{REQUEST_URI} ^/([^.]+)$ RewriteCond %{DOCUMENT_ROOT}/cache/%1.html -f RewriteRule ^/[^.]+$ /cache/%1.html [QSA,L] RewriteCond %{THE_REQUEST} ^(GET|HEAD) RewriteCond %{DOCUMENT_ROOT}/cache/index.html -f RewriteRule ^/$ /cache/index.html [QSA,L] </VirtualHost> I found the above at: http://www.alfajango.com/blog/make-sure-your-rails-application-is-actually-caching-and-not-just-pretending/ > It is easy to call "cgi.setCache(true);" though. > >> Then it doesn't even need to start the application if the cache is >> available. > > It's better with a client side cache. If it's available, you don't > have to go to the server at all! Yes of course, that is preferred. > Server side caching is something I haven't done yet; it's never > been useful to me. -- /Jacob Carlborg

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