bun.sh/bench/snippets/dns.ts

import { dns } from "bun";
import { bench, run, group } from "mitata";

async function forEachBackend(name, fn) {
  group(name, () => {
    for (let backend of [
      "libc",
      "c-ares",
      process.platform === "darwin" ? "system" : "",
    ].filter(Boolean))
      bench(backend, fn(backend));
  });
}

forEachBackend("dns.lookup remote x 50", (backend) => async () => {
  const run = () =>
    dns
      .lookup(Math.random().toString(16) + ".example.com", { backend })
      .catch(() => {});
  var remain = 16;
  var done;
  await new Promise((resolve) => {
    for (var i = 0; i < 16; i++)
      run().finally(() => {
        remain--;
        if (remain === 0) {
          done();
        }
      });
    done = resolve;
  });
});

forEachBackend("(cached) dns.lookup remote x 50", (backend) => {
  var tld = "example.com";
  const run = () => dns.lookup(tld, { backend }).catch(() => {});

  return async () => {
    const total = 50;
    var remain = total;
    var done;
    await new Promise((resolve) => {
      for (var i = 0; i < total; i++)
        run().finally(() => {
          remain--;
          if (remain === 0) {
            done();
          }
        });
      done = resolve;
    });
  };
});

forEachBackend(
  "(cached in batch) dns.lookup remote x 50",
  (backend) => async () => {
    var tld = Math.random().toString(16) + ".example.com";
    const run = () => dns.lookup(tld, { backend }).catch(() => {});
    const total = 50;
    var remain = total;
    var done;
    await new Promise((resolve) => {
      for (var i = 0; i < total; i++)
        run().finally(() => {
          remain--;
          if (remain === 0) {
            done();
          }
        });
      done = resolve;
    });
  },
);

await run();