I didn't know you could turn off caching in chrome. I'll have to take a better look into their dev tools. Once you figure this out, it could make a nice blog post on how to use front end + backend analytics to debug and speed up performance problems.
On Wed, Feb 19, 2014 at 12:02 PM, Rodrigo Rosenfeld Rosas < [email protected]> wrote: > On 19-02-2014 13:44, richard schneeman wrote: > > This functionality does not come from Rails, but rather Rack::Runtime ( > http://guides.rubyonrails.org/configuring.html#configuring-middleware) > you can see the middleware here: > https://github.com/rack/rack/blob/master/lib/rack/runtime.rb. It looks > pretty simple, i'm not sure if it is streaming aware. > > For different latencies regarding assets, i'm guessing that chrome is > perhaps doing some caching? How much latency do you get when you hit that > CSS from a new incognito window? > > > I don't need an incognito window to force skipping any caching, I just > check "Disable cache (while DevTools is open)". I did that and I can see > from the Network pane that the response status was 200, and it took 16ms of > latency + 30ms of "Receiving" time for a JS asset. > > What I mean is that most probably the web server (Puma, Webrick) is not > the cause for such a big latency... So maybe there's something more > happening that is not registered by that middleware and I'd like to know if > there's anyway I could understand what else it could be and if I'm able to > optimize it... > > Just in case you're curious, I tested it in an incognito window and the > result is the same as disabling cache. > > > From my understanding rendering as a stream won't make the whole page > load faster, it will just send elements to the browser as soon as they are > ready so the HTTP request would still take just as long, but the end user > sees content sooner and the browser has more time to parse and fetch > CSS/JS/etc. Perhaps chrome is measuring the request time? > > > I understand that and that's exactly my intention. I want Chrome to > download the assets while the page is loading but I see that it won't > download them until the page finishes loading, which makes sense since I > get about 3ms of "Receiving" time. What I mean is that rendering with > "stream: true" is not helping at all and it makes no difference if I use > normal rendering (except for this bug I reported yesterday: > https://github.com/rails/rails/issues/14093) > > Chrome reports me all timings separately: "Blocking", "Sending", "Waiting" > and "Receiving". The waiting part is taking 99% of the total time. Do you > get different results? > > I have even included this in one of my partials: > > <% sleep 1 -%> > > Guess what: "Waiting: 1.1s" > > So, I guess the problem is that streaming doesn't seem to be working > actually. > > Now that I figured this out, I'll try to reproduce in a separate > application and if I can, I'll report another bug for template streaming > rendering. > > Thank you for helping, Richard. > > Cheers, > Rodrigo. > > > > > On Wed, Feb 19, 2014 at 8:42 AM, Rodrigo Rosenfeld Rosas < > [email protected]> wrote: > >> As far as I understand, Rails uses a middleware by default that will send >> the total time spent on a request in the Rails side in the X-Runtime HTTP >> header. >> >> But it doesn't seem to be reliable in the sense that when I perform a >> request against http://localhost:3000/ (development environment, tested >> with both Puma and Webrick), I get 10ms of latency when serving some CSS >> assets but 109ms of latency for the index page. When I look at the header >> for the same request, I get "X-Runtime: 0.034849". >> >> Here's how it reports the timing in the server logs: >> >> Completed 200 OK in 22ms (Views: 1.4ms | Sequel: 13.2ms) >> Rendered search/_fields_finder.html.erb (0.0ms) >> Rendered search/_left_pane.html.erb (0.7ms) >> Rendered search/_index.html.erb (8.9ms) >> Rendered transactions/_list.html.erb (0.0ms) >> Rendered search/_saved_searches_dialogs.html.erb (0.2ms) >> Rendered search/_saved.html.erb (0.5ms) >> Rendered main/_change_log.html.erb (0.1ms) >> Rendered main/_glossary.html.erb (0.0ms) >> Rendered themes/default/_footer.html.erb (0.1ms) >> Rendered main/index.html.erb within layouts/main (70.5ms) >> >> This happens because I'm using "render stream: true" in that action, but >> I'd expect the latency to be reduced when looking at the Chrome reported >> timing, but it doesn't matter if I render with "stream: true" or not, the >> latency reported by Chrome is always about 100ms. >> >> Am I missing something? >> >> Thanks in advance, >> Rodrigo. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Ruby on Rails: Core" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/rubyonrails-core. >> For more options, visit https://groups.google.com/groups/opt_out. >> > > -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/rubyonrails-core. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/rubyonrails-core. > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/rubyonrails-core. For more options, visit https://groups.google.com/groups/opt_out.
