Benchmarking Task prerequisite performance between 2 implementations

The task

Implement a data structure that can hold tasks which are callables accepting 2 parameters: input which is the input to the task and prerequisite which is a number representing some precondition

Tasks may or may not have a prerequisite if they do not have one the precondition is considered met by default.

We want to be able to execute a collection of heterogeneous tasks.

Implementation

We'll consider two implementations:

• The first one ( V1 ) has an optional data member called prereq which is checked before executing the callable member (see the tick methods in tasks/src/lib.rs or js-bench/main.js)
• The second implementation ( V2 ) replaces the internal task with one that checks for the precondition if a precondition is required (see the tick methods in tasks/src/lib.rs or js-bench/main.js). This way the condition check is omitted altogether if the task has no preconditions

Benchmarks

We'll iterate over a list of a million tasks that are created by the following rules:

- If the index of the task modulo 128 is 0 then the task has a prerequisite of 32 and returns the input
- Else the task has no precondition and returns `input * 2`

We'll use fix input while iterating, all tasks are called with input == 1 and prerequisite == index of the task We'll measure the average time to iterate and execute all tasks

Structure

+ js-bench/   # The JavaScript benchmark
    main.js

+ wasm-bench/ # The Rust WASM benchmarks and the native benchmarks
  ~ src/
      main.rs 
    Cargo.toml
    Web.toml

Environment

The benchmarks were ran on a Intel Code i7-8700 processor
The Rust source was compiled using cargo 1.37.0-nightly (4c1fa54d1 2019-06-24) and cargo-web 0.6.25
The WASM and JS tests were ran using Node.JS 10.15.1

Running

• Native: cd wasm-bench then cargo bench
• WASM: cd wasm-bench then cargo web build --release then node target/wasm32-unknown-unknown/release/wasm-bench.js
• JS:cd js-bench then node main.js

Results

• Running cargo bench (note 1.8 million ns == 1.8 ms):

  • test tests::v1 ... bench: 2,891,097 ns/iter (+/- 137,348)
  • test tests::v2 ... bench: 2,783,485 ns/iter (+/- 199,645)
  • test tests::v3 ... bench: 2,269,960 ns/iter (+/- 84,831)
  • test tests::v4 ... bench: 3,859,810 ns/iter (+/- 247,616)

• Running cargo web build --release then node wasm-bench.js in the target directory to execute the wasm code:

  • V1: 5.698999881744385 ms
  • V2: 5.040999889373779 ms
  • V3: 3.9130001068115234 ms
  • V4: 7.288000106811523 ms

• Running node main.js in the js-bench directory:

  • V1: 15.043 ms
  • V2: 14.371 ms