Slow json rendering

Hi,

I have around 2000 objects to render. Unfortunately the view rendering
with jbuilder takes very long time, although the objects are small like
this:

center: {lat: 48.8130685274225, lon: 10.0405494495457}
lat: 48.8130685274225
lon: 10.0405494495457
n: “Aalen/Hirtenteich”
st: null
sy: null

The result query I pass to the view looks like this
@resorts = Resort.where(:id => resort_ids).includes(:snow_reports)

A resort has many snow_reports. st and sy are fields from snow reports.

the view looks like this:

json.array!(@resorts) do |resort|
json.cache!(“resort_light_#{resort.id}”) do

#json.partial! 'json_partials/snow_in_resort', resort: resort
json.n resort.name
json.sy resort.try(:snow_reports).last.try(:snow_valley) if

resort.snow_reports
json.st resort.try(:snow_reports).last.try(:snow_summit) if
resort.snow_reports
json.center do
json.lat resort.centroid.lat
json.lon resort.centroid.lon
end
end
end

Rendered resorts/find.json.jbuilder (1649.0ms)
Completed 200 OK in 1889ms (Views: 1593.1ms | ActiveRecord: 77.8ms |
Solr: 0.0ms)
In development mode the request takes 5s in chrome to run.

The first thing I ve done to speed up is changing the json gem to

  gem 'oj'
  gem 'oj_mimic_json'

It speeds up slightly but not enough. I also tried active model
serialization wich was about the same time, so I prefer to stick to
jbuilder since it is convenient to assemble json objects.
So how can I speed up rendering?

Help is highly appreciated since I am stuck for a week now.

have you tried #as_json?

On Monday, 15 December 2014 14:59:02 UTC-5, Ruby-Forum.com User wrote:

lat: 48.8130685274225

the view looks like this:

json.array!(@resorts) do |resort|
json.cache!(“resort_light_#{resort.id}”) do

#json.partial! 'json_partials/snow_in_resort', resort: resort
json.n resort.name
json.sy resort.try(:snow_reports).last.try(:snow_valley) if

resort.snow_reports

How many snow reports does a typical resort have? I ask because you’re
loading all of them with the includes above, but only using the last
one. If you’ve got 2000 resorts and each one has 100 reports or so, that
means instantiating 200000 SnowReport objects, and that is not going to
be
fast.

–Matt J.