Lint large test repos in parallel (via worker threads) for shorter run times.

test/markdownlint-test-parallel.js

@@ -0,0 +1,44 @@
+// @ts-check
+
+"use strict";
+
+// eslint-disable-next-line n/no-unsupported-features/node-builtins
+const { availableParallelism } = require("node:os");
+const { Worker } = require("node:worker_threads");
+const markdownlintSync = require("../lib/markdownlint").sync;
+
+/**
+ * Lint specified Markdown files (using multiple threads).
+ *
+ * @param {import("../lib/markdownlint").Options} options Configuration options.
+ * @returns {Promise<import("../lib/markdownlint").LintResults>} Results object.
+ */
+function markdownlintParallel(options) {
+  const workerCount = availableParallelism();
+  const files = options.files || [];
+  const chunkSize = Math.ceil(files.length / workerCount);
+  const promises = [];
+  for (let i = 0; i < workerCount; i++) {
+    promises.push(new Promise((resolve, reject) => {
+      const workerData = {
+        ...options,
+        "files": files.slice(i * chunkSize, (i + 1) * chunkSize)
+      }
+      const worker = new Worker(__filename.replace(/parallel\.js$/, "worker.js"), { workerData });
+      worker.on("message", resolve);
+      worker.on("error", reject);
+    }));
+  }
+  return Promise.all(promises).then((workerResults) => {
+    const combinedResults = markdownlintSync(null);
+    for (const workerResult of workerResults) {
+      // eslint-disable-next-line guard-for-in
+      for (const result in workerResult) {
+        combinedResults[result] = workerResult[result];
+      }
+    }
+    return combinedResults;
+  });
+}
+
+module.exports = markdownlintParallel;

test/markdownlint-test-repos-dotnet-docs.js

@@ -10,5 +10,5 @@ test("https://github.com/dotnet/docs", (t) => {
   const rootDir = "./test-repos/dotnet-docs";
   const globPatterns = [ join(rootDir, "**/*.md") ];
   const configPath = join(rootDir, ".markdownlint-cli2.jsonc");
-  return lintTestRepo(t, globPatterns, configPath);
+  return lintTestRepo(t, globPatterns, configPath, true);
 });

test/markdownlint-test-repos-mdn-content.js

@@ -10,5 +10,5 @@ test("https://github.com/mdn/content", (t) => {
   const rootDir = "./test-repos/mdn-content";
   const globPatterns = [ join(rootDir, "**/*.md") ];
   const configPath = join(rootDir, ".markdownlint-cli2.jsonc");
-  return lintTestRepo(t, globPatterns, configPath);
+  return lintTestRepo(t, globPatterns, configPath, true);
 });

test/markdownlint-test-repos.js

@@ -5,7 +5,8 @@
 const { join } = require("node:path").posix;
 const jsoncParser = require("jsonc-parser");
 const jsYaml = require("js-yaml");
-const markdownlint = require("../lib/markdownlint");
+const { markdownlint, readConfig } = require("../lib/markdownlint").promises;
+const markdownlintParallel = require("./markdownlint-test-parallel");
 
 /**
  * Lints a test repository.
@@ -13,9 +14,10 @@ const markdownlint = require("../lib/markdownlint");
  * @param {Object} t Test instance.
  * @param {string[]} globPatterns Array of files to in/exclude.
  * @param {string} configPath Path to config file.
+ * @param {boolean} [parallel] True to lint in parallel.
  * @returns {Promise} Test result.
  */
-async function lintTestRepo(t, globPatterns, configPath) {
+async function lintTestRepo(t, globPatterns, configPath, parallel) {
   t.plan(1);
   const { globby } = await import("globby");
   const jsoncParse = (json) => {
@@ -25,7 +27,7 @@ async function lintTestRepo(t, globPatterns, configPath) {
   const yamlParse = (yaml) => jsYaml.load(yaml);
   return Promise.all([
     globby(globPatterns),
-    markdownlint.promises.readConfig(configPath, [ jsoncParse, yamlParse ])
+    readConfig(configPath, [ jsoncParse, yamlParse ])
   ]).then((globbyAndReadConfigResults) => {
     const [ files, rawConfig ] = globbyAndReadConfigResults;
     // eslint-disable-next-line no-console
@@ -37,7 +39,7 @@ async function lintTestRepo(t, globPatterns, configPath) {
           v
         ])
     );
-    return markdownlint.promises.markdownlint({
+    return (parallel ? markdownlintParallel : markdownlint)({
       files,
       config
     }).then((results) => {

test/markdownlint-test-worker.js

@@ -0,0 +1,16 @@
+// @ts-check
+
+"use strict";
+
+const { parentPort, workerData } = require("node:worker_threads");
+const markdownlint = require("../lib/markdownlint").promises.markdownlint;
+
+// eslint-disable-next-line unicorn/prefer-top-level-await
+markdownlint(workerData).then((lintResults) => {
+  // @ts-ignore
+  parentPort.
+    // eslint-disable-next-line unicorn/require-post-message-target-origin
+    postMessage(lintResults);
+  // eslint-disable-next-line n/no-process-exit
+  process.exit();
+});