Benchmarking Dynamic Dispatch vs. Polymorphic Input

.gitignore

node_modules/

README.md

Benchmarking Dynamic Dispatch vs. Polymorphic Input

This is an attempt to see if JIT-ed codepaths throw off a microbenchmark.

Running the microbenchmark produces

$ npm run benchmark

> @ benchmark .../fee7792dd695940483b3c0cdbfd8a78f
> node index.js

withDynamicDispath x 99,765,425 ops/sec ±2.36% (79 runs sampled)
withPolymorphic x 45,310,089 ops/sec ±1.61% (84 runs sampled)

The comparison is between invoking a function that accepts a polymorphic input (polymorphic since it can be a 2D or 3D point)

function polymorphicSum(point) {
  return point.x + point.y + (point.z || 0);
}

and using dynamic dispatch to invoke two different specialized functions

function sum2D(point) {
  return point.x + point.y;
}

function sum3D(point) {
  return point.x + point.y + point.z;
}

These are invoked by "randomly" deciding at call time to use a 2D or 3D point so each of them will get invoked in the "same" way.

index.js

const Benchmark = require("benchmark");

function polymorphicSum(point) {
  return point.x + point.y + (point.z || 0);
}

function sum2D(point) {
  return point.x + point.y;
}

function sum3D(point) {
  return point.x + point.y + point.z;
}

function withPolymorphic() {
  if (Math.random() > 0.5) {
    return polymorphicSum({ x: 10.5, y: -11.75 });
  }
  return polymorphicSum({ x: 171.25, y: -3.0, z: -6.75 });
}

function withDynamicDispath() {
  if (Math.random() > 0.5) {
    return sum2D({ x: 10.5, y: -11.75 });
  }
  return sum3D({ x: 171.25, y: -3.0, z: -6.75 });
}

function main() {
  const suite = new Benchmark.Suite();
  suite
    .add("withDynamicDispath", withDynamicDispath)
    .add("withPolymorphic", withPolymorphic)
    .on("cycle", function (event) {
      console.log(String(event.target));
    })
    .run({ async: true });
}

if (require.main === module) {
  main();
}

package-lock.json

{
  "requires": true,
  "lockfileVersion": 1,
  "dependencies": {
    "benchmark": {
      "version": "2.1.4",
      "resolved": "https://registry.npmjs.org/benchmark/-/benchmark-2.1.4.tgz",
      "integrity": "sha1-CfPeMckWQl1JjMLuVloOvzwqVik=",
      "requires": {
        "lodash": "^4.17.4",
        "platform": "^1.3.3"
      },
      "dependencies": {
        "lodash": {
          "version": "4.17.15",
          "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.15.tgz",
          "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A=="
        }
      }
    },
    "platform": {
      "version": "1.3.5",
      "resolved": "https://registry.npmjs.org/platform/-/platform-1.3.5.tgz",
      "integrity": "sha512-TuvHS8AOIZNAlE77WUDiR4rySV/VMptyMfcfeoMgs4P8apaZM3JrnbzBiixKUv+XR6i+BXrQh8WAnjaSPFO65Q=="
    },
    "prettier": {
      "version": "2.0.5",
      "resolved": "https://registry.npmjs.org/prettier/-/prettier-2.0.5.tgz",
      "integrity": "sha512-7PtVymN48hGcO4fGjybyBSIWDsLU4H4XlvOHfq91pz9kkGlonzwTfYkaIEwiRg/dAJF9YlbsduBAgtYLi+8cFg=="
    }
  }
}

package.json

{
  "scripts": {
    "benchmark": "node index.js",
    "prettier": "prettier index.js --write"
  },
  "prettier": {
    "printWidth": 120,
    "quoteProps": "consistent",
    "semi": true,
    "singleQuote": false,
    "trailingComma": "all"
  },
  "dependencies": {
    "benchmark": "2.1.4",
    "prettier": "2.0.5"
  }
}