Two type of tasks

• CPU Bound
• IO Bound

Core concept

Make full use of CPU

CPU Bound

Solution: return cpu time back to user space

• less scheduling of threads
• dedicated core for threads
• make full use of cache
• branch predicting friendly
• SIMD

problem: to much waste of time on scheduling

IO Bound

Solution: give back cpu time back to kernel

• less threads
• callback / coroutine
• reactor & proactor

problem：too much threads waiting blocked cpu

IO & Compute Both Bounded?

Database

Scenario

Analytics Service

Main task type：map/reduce on prefetched cache

Soluiton 1

Ruby + Rust

Ruby

Rainbows for async

Rust

Computation

Expose Pure FFI

Ruby Native Extension

Wrapper at Ruby side

Problems

• Eventmachine is a bullshit
• Boilerplates
• FFI safety

• Mandatory Free

Why Rust

Safety

Rust is a systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety.

As a NIF library is dynamically linked into the emulator process, this is the fastest way of calling C-code from Erlang (alongside port drivers). Calling NIFs requires no context switches. But it is also the least safe, because a crash in a NIF brings the emulator down too.

------

http://erlang.org/doc/tutorial/nif.html

Performance

Techempower round 14

alioth benchmark game (https://strk.ly/VJ)

”Rust now beats C++ in many benchmarks and is on par with others“

Interesting

• Meta Programming (macro)
• Type Inference
• Trait Mixin

Solution 2

Elixir + Rust

Why?

• Elixir's high concurrency

• Better interface between Elixir & Rust (Rustler)

But cons:

• Elixir is much slower

• Elixir has less 3rd-party libraries

• Exotic grammar

• Not compatible with Strikingly's deploy logic

Step by step

Translate interface code

Implement the server

System structure

Caveat

• You need a customized erlang VM (https://hub.docker.com/r/wooya/elixir-dirty-scheduler/)

• elixir --erl "-smp +K true +A 10 +SDio 300 +SDcpu 100:100" -S mix phoenix.server

Deployed since 2016.11

0 Down time

Improvements

• Use proactor to read data from redis
• Use Weld to improve throughput

Weld: computation engine from Stanford