Speed up collection rendering and add support for multifetch collection handling #501

yuki24 · 2021-02-22T01:42:24Z

This PR mainly improves two things:

Speed up collection rendering by taking advantage of the existing collection renderer in ActionView
Add support for multifetch collection handling to make it more efficient

Basically, the idea is to create a class that extends the ActionView::CollectionRenderer (or ActionView::PartialRenderer in Rails 6.0) and use the ScopedIterator on each iteration of the collection, so that we will be able to render JSON for each element without having to find_template, which is known to be slow. Aside from that, we will be able to use other features of the render method as well because it's the same render we use in a typical Rails view.

The biggest winner here is the ability to use cached: true that multi-fetches fragments in one shot from the cache store. This was originally proposed by @dhh here: #399 (comment), but we haven't been able to implement it because of the tricky rendering logic in Jbuilder. However since Rails 6.0, the code for collection caching has been improved and more structured. As a result, I was able to extend and re-use the renderer in Jbuilder.

Here are the performance comparison:

Variant	multifetch	Time per request [ms]
Version 2.10.1 (without caching)	-	882.299
Version 2.10.1 (with the existing `json.cache!`)	❌	103.909
This PR (without `cached: true` or cold)	-	662.832
This PR (with `cached: true`, warmed up)	✅	96.911

As you can see, collection rendering is now faster by 200ms in the example below, with the ability fo multi-fetch if needed!

That means if there is a record that was updated, it is going to be the only record that will get re-generated:

$ rails c
> City.first.touch
=> true

And when curl http://localhost:3000/states is run, the following log would be displayed:

Started GET "/states" for ::1 at 2021-02-22 10:04:08 -0500
Processing by StatesController#index as */*
  Rendering states/index.json.jbuilder
  State Load (0.4ms)  SELECT "states".* FROM "states"
  ↳ app/views/states/index.json.jbuilder:1
  City Load (5.2ms)  SELECT "cities".* FROM "cities" WHERE "cities"."state_id" = ?  [["state_id", 129]]
  ↳ app/views/states/index.json.jbuilder:1
  Rendered collection of cities/_city.json.jbuilder [19 / 20 cache hits] (Duration: 2.9ms | Allocations: 1816)
  Rendered collection of states/_state.json.jbuilder [50 / 51 cache hits] (Duration: 107.3ms | Allocations: 59640)
  Rendered states/index.json.jbuilder (Duration: 160.0ms | Allocations: 125006)
Completed 200 OK in 161ms (Views: 155.0ms | ActiveRecord: 5.7ms | Allocations: 125215)

Now the existing cache has been re-used and there is only one fragment that got re-generated! This is a huge performance boost, and I have already confirmed that this works pretty well with one of my clients.

The major downside of this is that we will have to drop support for Rails 5.2 and earlier. Because the collection caching logic isn't as extendable as it is in Rails 6.0 and later, it was a lot more complicated to do the same in Rails 5.2. I thought that was a stopping point and decided to send this PR.

Let me know what you all think about this. Thanks!

Remaining Todos

Keep the compatibility with Rails <= 5.2
Add support for Rails 6.0
Add a bit more test coverage around the cached: true usage
Add documentation to Jbuilder::CollectionRenderer
Update README

Example code

The data is based on the 50 U.S. states and cities for each state. The import script could be found here. The /states.json endpoint returns a list of all the 50 states and the first 20 cities for each state.

# app/models/state.rb
#
# t.string "name"
# t.string "abbreviation"
# t.datetime "created_at", precision: 6, null: false
# t.datetime "updated_at", precision: 6, null: false
class State < ApplicationRecord
  has_many :cities
end

# app/models/city.rb
#
# t.integer "state_id"
# t.string "name"
# t.string "county"
# t.datetime "created_at", precision: 6, null: false
# t.datetime "updated_at", precision: 6, null: false
class City < ApplicationRecord
  belongs_to :state, touch: true
end

# app/controllers/states_controller.rb
class StatesController < ApplicationController
  def index
    @states = State.all.includes(:cities)
  end
end

# app/views/states/index.json.jbuilder
json.array! @states, partial: "states/state", as: :state, cached: true

# app/views/states/_state.json.jbuilder
json.extract! state, :id, :name, :abbreviation, :created_at, :updated_at
json.url state_url(state, format: :json)

json.cities state.cities.first(20), partial: "cities/city", as: :city, cached: true

# app/views/cities/_city.json.jbuilder
json.extract! city, :id, :name, :county, :created_at, :updated_at

Raw results of `$ ab -n100 http://localhost:3000/states.json`

Version 2.10.1

This is ApacheBench, Version 2.3 <$Revision: 1879490 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient).....done


Server Software:
Server Hostname:        localhost
Server Port:            3000

Document Path:          /states
Document Length:        140948 bytes

Concurrency Level:      1
Time taken for tests:   88.230 seconds
Complete requests:      100
Failed requests:        0
Total transferred:      14141100 bytes
HTML transferred:       14094800 bytes
Requests per second:    1.13 [#/sec] (mean)
Time per request:       882.299 [ms] (mean)
Time per request:       882.299 [ms] (mean, across all concurrent requests)
Transfer rate:          156.52 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.0      0       0
Processing:   586  882 182.6    831    1568
Waiting:      586  882 182.6    831    1568
Total:        586  882 182.6    831    1568

Percentage of the requests served within a certain time (ms)
  50%    831
  66%    899
  75%    964
  80%    982
  90%   1130
  95%   1268
  98%   1527
  99%   1568
 100%   1568 (longest request)

Version 2.10.1 (with the existing json.cache!)

This is ApacheBench, Version 2.3 <$Revision: 1879490 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient).....done


Server Software:
Server Hostname:        localhost
Server Port:            3000

Document Path:          /states
Document Length:        140948 bytes

Concurrency Level:      1
Time taken for tests:   10.391 seconds
Complete requests:      100
Failed requests:        0
Total transferred:      14141100 bytes
HTML transferred:       14094800 bytes
Requests per second:    9.62 [#/sec] (mean)
Time per request:       103.909 [ms] (mean)
Time per request:       103.909 [ms] (mean, across all concurrent requests)
Transfer rate:          1329.01 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0       1
Processing:    92  104   9.8    100     144
Waiting:       92  103   9.8     99     144
Total:         92  104   9.8    100     144

Percentage of the requests served within a certain time (ms)
  50%    100
  66%    102
  75%    107
  80%    111
  90%    122
  95%    125
  98%    129
  99%    144
 100%    144 (longest request)

With this PR (without cached: true)

This is ApacheBench, Version 2.3 <$Revision: 1879490 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient).....done


Server Software:
Server Hostname:        localhost
Server Port:            3000

Document Path:          /states
Document Length:        140948 bytes

Concurrency Level:      1
Time taken for tests:   66.283 seconds
Complete requests:      100
Failed requests:        0
Total transferred:      14141100 bytes
HTML transferred:       14094800 bytes
Requests per second:    1.51 [#/sec] (mean)
Time per request:       662.832 [ms] (mean)
Time per request:       662.832 [ms] (mean, across all concurrent requests)
Transfer rate:          208.34 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.0      0       0
Processing:   427  663 229.6    570    1225
Waiting:      426  662 229.6    570    1225
Total:        427  663 229.6    570    1225

Percentage of the requests served within a certain time (ms)
  50%    570
  66%    663
  75%    688
  80%    715
  90%   1134
  95%   1170
  98%   1212
  99%   1225
 100%   1225 (longest request)

With this PR (with cached: true)

$ ab -n100 http://localhost:3000/states
This is ApacheBench, Version 2.3 <$Revision: 1879490 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient).....done


Server Software:
Server Hostname:        localhost
Server Port:            3000

Document Path:          /states
Document Length:        140948 bytes

Concurrency Level:      1
Time taken for tests:   9.691 seconds
Complete requests:      100
Failed requests:        0
Total transferred:      14141100 bytes
HTML transferred:       14094800 bytes
Requests per second:    10.32 [#/sec] (mean)
Time per request:       96.911 [ms] (mean)
Time per request:       96.911 [ms] (mean, across all concurrent requests)
Transfer rate:          1424.99 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.0      0       0
Processing:    73   97  20.3     94     202
Waiting:       73   96  20.3     94     202
Total:         74   97  20.3     94     202

Percentage of the requests served within a certain time (ms)
  50%     94
  66%    102
  75%    108
  80%    110
  90%    122
  95%    138
  98%    146
  99%    202
 100%    202 (longest request)

yuki24 · 2021-02-22T03:41:41Z

I believe we should look at #502 and merge it first since the CI builds are a little out of date.

kaspth · 2021-02-22T09:05:36Z

Really cool stuff! We could consider shipping this as a major version bump and drop support for < 6.1 and Ruby < 2.7? It looks like we'd need to trim 5.2 and < 2.5 support anyway.

yuki24 · 2021-02-23T16:32:16Z

We can also add some sort of feature detection and fall back to the old way on Rails <= 5.2. That way users will easily be able to upgrade to the newer versions of Jbuilder and get a performance boost for free after upgrading Rails. Any thoughts?

kaspth · 2021-02-23T17:04:13Z

Yeah, we can go for that version too and then ditch 5.2 support separately 👍

yuki24 · 2021-02-24T02:11:21Z

Alright, Rails <= 5.2 compatibility is back and additional tests are in place. Now I have add a bit more documentation and this should be good for another round of review.

yuki24 · 2021-02-26T19:55:33Z

README.md

@@ -253,9 +255,17 @@ json.cache_if! !admin?, ['v1', @person], expires_in: 10.minutes do
 end
 ```

-If you are rendering fragments for a collection of objects, have a look at
-`jbuilder_cache_multi` gem. It uses fetch_multi (>= Rails 4.1) to fetch


I do not believe we have to mention it any more as Jbuilder will have it built-in once this PR is merged. So I just replaced it with how cached: true could be used on collection rendering.

yuki24 · 2021-02-26T19:57:18Z

All the todos are done now and this should be good for review. Thanks!

lib/jbuilder/collection_renderer.rb

kaspth · 2021-03-07T18:53:02Z

Super cool! A separate PR would be to set up CI running on Rails head and automatic once-a-day builds so we don't cause regressions with other refactorings on the Rails side. …would also be good to switch to Buildkite, but @matthewd may remember how to do that.

lib/jbuilder/jbuilder_template.rb

yuki24 · 2021-03-09T02:46:24Z

Updated the code as suggested. let me know if there is anything I can do.

tomazzlender · 2021-05-18T19:17:25Z

Is this ready to be merged or is there something missing?

Amazing work @yuki24, I'm looking forward to using this!

yuki24 · 2021-06-26T19:07:18Z

There was a bug where the type of the JSON changes when the collection is empty. Fixed and added a test that covers this case:

jbuilder/test/jbuilder_template_test.rb

Lines 287 to 292 in 00c92ef

    
           test "returns an empty array for an empty collection" do 
        
             result = render('json.array! @posts, partial: "post", as: :post, cached: true', posts: []) 
        
             # Do not use #assert_empty as it is important to ensure that the type of the JSON result is an array. 
        
             assert_equal [], result 
        
           end

ghost · 2021-11-12T21:28:37Z

+1

dhh · 2021-11-13T12:16:36Z

Excellent work, @yuki24! There's some issues with rails master. Could you have a look? I'll get it merged!

yuki24 · 2021-11-14T08:21:18Z

@dhh The test seems to be failing even on the master branch, so I sent a separate PR to fix that #513. Once that PR is merged everything including this PR should be green.

Turn page_types into array since JBuilder 2.11.3 (rails/jbuilder#501) requires collection to respond to `empty?`, which `Enumerable` does not provide. See also rails/jbuilder#514 REDMINE-19357

Turn enumerables into arrays since JBuilder 2.11.3 (rails/jbuilder#501) requires collection to respond to `empty?`, which `Enumerable` does not provide. See also rails/jbuilder#514 REDMINE-19357

Jbuilder since #501 depends on Action View so we need to make it a dependency. Also we should be requiring both action_view and active_support before using it. Closes #518.

Turn enumerables into arrays since JBuilder 2.11.3 (rails/jbuilder#501) requires collection to respond to `empty?`, which `Enumerable` does not provide. See also rails/jbuilder#514 REDMINE-19357

@Racers

# Goal We should be able to effectively render collection of data and be able to cache it. ## Problem statement Previously, we have used following code to render collection: ```ruby pb.cache!(@account.offers_cache_key, expires_in: 12.hours) do pb.featured_offers @featured_offers, partial: "offer", as: :offer pb.normal_offers @normal_offers, partial: "offer", as: :offer end ``` But we need to introduce fragment caching to offers, since list cache has high miss rate. This is how implementing fragment caching in pbbuilder should look like: ```ruby pb.cache!(@account.offers_cache_key, expires_in: 12.hours) do pb.featured_offers partial: "offer", as: offer, collection: @featured_offers, cached: true pb.normal_offers partial: "offer", as: :offer, collection: @normal_offers, cached: true end ``` This syntax is heavily inspired by jbuilder. Here is list of examples from that gem that uses cached: and collection: attributes. ```ruby json.partial! partial: 'posts/post', collection: @posts, as: :post ``` ```ruby json.partial! 'posts/post', collection: @posts, as: :post ``` ```ruby json.partial! "post", collection: @posts, cached: true, as: :post ``` ```ruby json.array! @posts, partial: "post", as: :post, cached: true ``` ```ruby json.array! @posts, partial: "posts/post", as: :post, cached: true ``` ```ruby json.comments @post.comments, partial: "comments/comment", as: :comment, cached:true ``` ## Proposed solution In this PR, we're implementing more effective rendering of collection with a help of `ActiveView::CollectionRenderer`. Support for caching of partial is currently not in the scope, but this will help implement caching and caching digest later. Following syntax should be supported: ```ruby pb.friends partial: "racers/racer", as: :racer, collection: @Racers ``` ```ruby pb.friends "racers/racer", as: :racer, collection: @Racers ``` Previous syntax works as it used to before. These will remain unchanged and will not use collection renderer (at least for now) ```ruby pb.partial! @racer, racer: Racer.new(123, "Chris Harris", friends) ``` ```ruby pb.friends @friends, partial: "racers/racer", as: :racer ``` ## TODO - [x] Add documentation for this change - [ ] Check performance difference between Collection Renderer and our approach. (without cache for now) - [x] It's using PartialRenderer with rails 7 now - this seems like a bug, it should use CollectionRenderer. ## Prior work Some inspiration for this PR could be found here: * rails/jbuilder#501 * https://github.com/rails/rails/blob/main/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb#L20 * https://github.com/rails/rails/tree/main/actionview collection_renderer * https://github.com/rails/rails/blob/main/actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb#L20

yuki24 force-pushed the faster-collection-rendering branch 3 times, most recently from 22cee2e to 3a5b475 Compare February 22, 2021 03:08

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yuki24 force-pushed the faster-collection-rendering branch from d35bae7 to 92fd6c0 Compare February 22, 2021 14:47

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yuki24 commented Feb 26, 2021

View reviewed changes

kaspth reviewed Mar 7, 2021

View reviewed changes

yuki24 commented Mar 9, 2021

View reviewed changes

lib/jbuilder/jbuilder_template.rb Outdated Show resolved Hide resolved

yuki24 force-pushed the faster-collection-rendering branch 2 times, most recently from 4e988ff to 8a4ae2d Compare March 9, 2021 02:38

yuki24 force-pushed the faster-collection-rendering branch from 8a4ae2d to 00c92ef Compare June 26, 2021 19:02

Speed up collection rendering and support collection caching

4df3418

yuki24 force-pushed the faster-collection-rendering branch from 3ae8a4c to 4df3418 Compare November 14, 2021 08:01

dhh merged commit d84c37d into rails:master Nov 14, 2021

yuki24 deleted the faster-collection-rendering branch November 14, 2021 11:59

cupakromer mentioned this pull request Nov 16, 2021

JBuilder 2.11.3 introduces an extra DB query when rendering collection partials #514

Closed

olliebennett mentioned this pull request Nov 17, 2021

Gem redundant after jbuilder 2.11.3 update? yonahforst/jbuilder_cache_multi#26

Open

tf mentioned this pull request Nov 22, 2021

JBuilder 2.11.3: "NoMethodError Exception: undefined method empty? for PG::Result" #516

Closed

tf mentioned this pull request Nov 24, 2021

Fix compatibility with JBuilder 2.11.3 codevise/pageflow#1757

Merged

rafaelfranca added a commit that referenced this pull request Dec 21, 2021

Require Rails frameworks before using

a2aacff

Jbuilder since #501 depends on Action View so we need to make it a dependency. Also we should be requiring both action_view and active_support before using it. Closes #518.

yuki24 added a commit to yuki24/jbuilder that referenced this pull request Feb 17, 2022

Fixed a bug where rails#501 broke compatibility with Enumerable

099c634

dhh pushed a commit that referenced this pull request Feb 17, 2022

Fixed a bug where #501 broke compatibility with Enumerable (#531)

63244d5

This was referenced Oct 20, 2023

failing test for cached:true parameter in collections cheddar-me/pbbuilder#42

Closed

Integrating collection renderer from ActionView cheddar-me/pbbuilder#43

Merged

skatkov mentioned this pull request Nov 2, 2023

Enable collection renderer for all collection-like objects cheddar-me/pbbuilder#50

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Speed up collection rendering and add support for multifetch collection handling #501

Speed up collection rendering and add support for multifetch collection handling #501

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Speed up collection rendering and add support for multifetch collection handling #501

Speed up collection rendering and add support for multifetch collection handling #501

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Example code

Raw results of $ ab -n100 http://localhost:3000/states.json

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Raw results of `$ ab -n100 http://localhost:3000/states.json`

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