Your guide to Ruby apps that can serve 10,000 requests per seconds, and beyond!

Don't believe the hype! The most performing are:

1. sinatra-unicorn. Docker
2. puma-mri-grape
3. rails-unicorn. Docker with nginx

Latency for sinatra-unicorn is esp. interesting 1.5 ms 0.2% (max 66.3 ms)

Numbers:

• unicorn-grape 9,305 rqs/seconds
• puma-rbx-grape 117 rqs/seconds
• puma-mri-grape 11,214 rqs/seconds
• puma-jruby-grape 200 rqs/seconds
• torqbox-grape 9,694 rqs/seconds
• trinidad-grape 7,235 rqs/seconds
• thin-grape 2,246 rqs/seconds
• jruby-padrino 200 rqs/seconds
• rbx-padrino 116 rqs/seconds
• puma-padrino 5,232 rqs/seconds
• thin-padrino 1,092 rqs/seconds
• torqbox-padrino 6,447 rqs/seconds
• trinidad-padrino 5,329 rqs/seconds
• unicorn-padrino 6,765 rqs/seconds
• rack 89,466 rqs/seconds
• rack-rbx 119 rqs/seconds
• racket-ws 2,015 rqs/seconds
• rails-torqbox 2,379 rqs/seconds
• rails-unicorn 6,125 rqs/seconds
• rails-stripped-ruby 6,942 rqs/seconds
• rails-stripped-jruby 2,570 rqs/seconds
• puma-mri-rails 4,027 rqs/seconds
• puma-rbx-rails 116 rqs/seconds
• puma-jruby-rails 200 rqs/seconds
• trinidad-rails 2,377 rqs/seconds
• sinatra-rbx-puma 118 rqs/seconds
• sinatra-trinidad 9,589 rqs/seconds
• sinatra-puma 12,761 rqs/seconds
• sinatra-thin 3,195 rqs/seconds
• sinatra-jruby-puma 200 rqs/seconds
• sinatra-unicorn 17,982 rqs/seconds
• sinatra-torqbox 18,340 rqs/seconds

• puma-jruby-grape 199 rqs/seconds
• puma-mri-grape 4,140 rqs/seconds
• unicorn-grape 4,203 rqs/seconds
• trinidad-grape 2,977 rqs/seconds
• puma-rbx-grape 115
• torqbox-padrino 3,807 rqs/seconds
• trinidad-padrino 3,462 rqs/seconds
• unicorn-padrino 3,691 rqs/seconds
• rbx-padrino 114 rqs/seconds
• thin-padrino 566 rqs/seconds
• jruby-padrino 200 rqs/seconds
• puma-padrino 4071 rqs/seconds
• rails-stripped-jruby 2,121 rqs/seconds
• rails-stripped-ruby 4,540 rqs/seconds
• rails-torqbox 2,428 rqs/seconds
• trinidad-rails 2,236 rqs/seconds
• rails-unicorn 4,264 rqs/seconds
• puma-jruby-rails 200 rqs/seconds
• puma-rbx-rails 114 rqs/seconds
• puma-mri-rails 3510 rqs/seconds
• sinatra-thin 1,284 rqs/seconds
• sinatra-trinidad 2,992 rqs/seconds
• sinatra-unicorn 7,464 rqs/seconds
• sinatra-jruby-puma 200 rqs/seconds
• sinatra-rbx-puma 116 rqs/seconds
• sinatra-puma 5,217 rqs/seconds
• sinatra-torqbox 2,818 rqs/seconds

• torqbox-grape 2,334 rqs/seconds
• trinidad-grape 2,602 rqs/seconds
• unicorn-grape 2,891 rqs/seconds
• puma-jruby-grape 398 rqs/seconds
• puma-mri-grape 4,966 rqs/seconds
• puma-rbx-grape 228 rqs/seconds
• thin-grape 659 rqs/seconds
• puma-padrino 2,247 rqs/seconds
• jruby-padrino 717 rqs/seconds
• thin-padrino 319 rqs/seconds
• trinidad-padrino 2,827 rqs/seconds
• unicorn-padrino 2,034 rqs/seconds
• torqbox-padrino 3,114 rqs/seconds
• rbx-padrino 430 rqs/seconds
• rails-torqbox 1,889 rqs/seconds
• trinidad-rails 2,126 rqs/seconds
• rails-unicorn 3,446 rqs/seconds
• puma-jruby-rails 394 rqs/seconds
• puma-rbx-rails 227 rqs/seconds
• puma-mri-rails 3,960 rqs/seconds
• sinatra-torqbox 2,426 rqs/seconds
• sinatra-puma 5,981 rqs/seconds
• sinatra-jruby-puma 779 rqs/seconds
• sinatra-rbx-puma 459 rqs/seconds
• sinatra-unicorn 5,612 rqs/seconds
• sinatra-thin 779 rqs/seconds
• sinatra-trinidad 2,663 rqs/seconds

Measure performance:

• Miniprofiler is a simple but effective mini-profiler
• NewRelic is a paid solution that will give you a lot of insights, esp. which requests are the slowest and where
• Google analytics can also help. For example, high bounce rates can mean either your site content is uninteresting, or it was too slow to load for them. Investigate!

It is very easy to create new objects and iterate through them with Ruby. What's less known are the consequences. Too much memory will be consumed. The Ruby heap will grow and eventually will take all the memory available.

Write code carefully. The best code is the one that does not exist. Here are different steps:

• Rails is a heavy framework requiring a lot of resources and only be used when programmer time is limited and if it has unique features for the use case. For a lightweight site or an API (web service), Sinatra is a good choice as seen on the benchmarks above.
• If you have to use Rails, consider deleting middlewares.
• Mutate the original object instead of creating new copies. For example, to remove whitespace, strip! will not create a new copy of the object compared to strip
• Tests and automated tests will surface poor code in your code. Make sure code coverage is maxed out!
• Instead of creating dedicated classes, modular code organization can give you a decent performance boost, especially for single atomic helper tasks. If you find yourself writing more than 15 lines to process a request, time to move it to a module
• Minimize the use of gems. Rails for example requires at least 40 gems. Consider if the extra overhead is worth it. Extra gems can also bring security issues, if they are from poor contributors.
• If the data is human-readable and correct but not beautiful, send them to the client-side. E.g.: date and time parsing, full names, currencies. Only process data that is private, business-sensitive
• Can you use memoization? There is a chance the same request has been processed before. Save the result in redis!
• Are you using over and over the standard map, each and blocks? Ruby has advanced methods such as flat_map, reverse_each, each_key that will not create new objects and will be an order or magnitude faster

• In Rails: Reduce the number of queries, especially N+1 queries
• Adding indexes
• Consider in-memory sqlite vs PostgreSQL in the case of non-concurrent writes
• Scaling reads by tuning SQL, looking at slow query log, NewRelic, and dTrace to find outliers
• Routing background jobs with unique usage characteristics to dedicated replicas
• Optimizing DB schema for high performance applications. Understanding MVCC and it's impact on application concurrency.
• Scaling writes by replacing high-throughput append-only DB tables (log tables) with non-database alternatives (rsyslog + flat files)

• Cache layers, one by one
• Put static files in CDNs, if possible

• Decouple long processes to a queue. Typically: image processing, video encoding, sending emails, uploading files, geo requests, etc. These can be in another app in go, java, or whatever tool is best for the job.
• Use a client-side Javascript framework

• Use React.js or another front-end framework
• Minify javascript and CSS
• Use async, whenever possible
• Display loader gifs and subtle animations to let the user the request is being processed