Evt

The Event Library that designed for Ruby 3.0 Fiber Scheduler.

This gem is still under development, APIs and features are not stable. Advices and PRs are highly welcome.

Features

IO Backend Support

	Linux	Windows	macOS	FreeBSD
io_uring	⚠️ (See 1)	❌	❌	❌
epoll	✅ (See 2)	❌	❌	❌
kqueue	❌	❌	✅ (⚠️ See 5)	✅
IOCP	❌	❌ (⚠️See 3)	❌	❌
Ruby (IO.select)	✅ (See 6)	✅ (⚠️See 4)	✅ (See 6)	✅ (See 6)

1. when liburing is installed. (Currently fixing)
2. when kernel version >= 2.6.9
3. WOULD NOT WORK until FILE_FLAG_OVERLAPPED is included in I/O initialization process.
4. Some I/Os are not able to be nonblock under Windows. Using POSIX select, SLOW. See Scheduler Docs.
5. kqueue performance in Darwin is very poor. MAY BE DISABLED IN THE FUTURE.
6. Using poll

Benchmark

The benchmark is running under v0.3.6 version. See example.rb in midori for test code, the test is running under a single-thread server.

The test command is wrk -t4 -c8192 -d30s http://localhost:8080.

All the systems have set their file descriptor limit to maximum.
On systems raising “Fiber unable to allocate memory”, sudo sysctl -w vm.max_map_count=1000000 is set.

OS	CPU	Memory	Backend	req/s
Linux	Ryzen 2700x	64GB	epoll	2035742.59
Linux	Ryzen 2700x	64GB	io_uring	require fixes
Linux	Ryzen 2700x	64GB	IO.select (using poll)	1837640.54
macOS	i7-6820HQ	16GB	kqueue	257821.78
macOS	i7-6820HQ	16GB	IO.select (using poll)	338392.12

We also test the server with Redis request, with a monkey-patched redis library. The example code is following:

require 'evt'
require 'midori'
require 'midori-contrib/redic'

Fiber.set_scheduler Evt::Scheduler.new
REDIS = Redic.new

class HelloWorldAPI < Midori::API
  get '/' do
    REDIS.call 'GET', 'foo'
  end
end

Fiber.schedule do
  Midori::Runner.new(HelloWorldAPI).start
end

The benchmark result is as following:

OS	CPU	Memory	Backend	req/s
Linux	Ryzen 2700x	64GB	epoll	378060.30
macOS	i7-6820HQ	16GB	kqueue	204460.32

Install

gem install evt

Usage

require 'evt'

rd, wr = IO.pipe
scheduler = Evt::Scheduler.new

Fiber.set_scheduler scheduler

Fiber.schedule do
  message = rd.read(20)
  puts message
  rd.close
end

Fiber.schedule do
  wr.write("Hello World")
  wr.close
end

# "Hello World"

Roadmap

• [x] Support epoll/kqueue/select
• [x] Upgrade to the latest Scheduler API
• [x] Support io_uring
• [x] Support iov features of io_uring
• [x] Support IOCP (NOT ENABLED YET)
• [x] Setup tests with Ruby 3
• [x] Selectable backend compilation by environment variable
• [ ] Support IOCP with iov features
• [ ] Setup more tests for production purpose
• [ ] Documentation for usages