chore: use os.availableParallelism when available

.yarn/versions/cad178bf.yml

@@ -0,0 +1,34 @@
+releases:
+  "@yarnpkg/cli": patch
+  "@yarnpkg/core": patch
+  "@yarnpkg/plugin-workspace-tools": patch
+
+declined:
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-exec"
+  - "@yarnpkg/plugin-file"
+  - "@yarnpkg/plugin-git"
+  - "@yarnpkg/plugin-github"
+  - "@yarnpkg/plugin-http"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-link"
+  - "@yarnpkg/plugin-nm"
+  - "@yarnpkg/plugin-npm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-pnp"
+  - "@yarnpkg/plugin-pnpm"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/builder"
+  - "@yarnpkg/doctor"
+  - "@yarnpkg/extensions"
+  - "@yarnpkg/nm"
+  - "@yarnpkg/pnpify"
+  - "@yarnpkg/sdks"

packages/plugin-workspace-tools/sources/commands/foreach.ts

@@ -5,12 +5,21 @@ import {formatUtils, miscUtils, structUtils}                         from '@yarn
 import {gitUtils}                                                    from '@yarnpkg/plugin-git';
 import {Command, Option, Usage, UsageError}                          from 'clipanion';
 import micromatch                                                    from 'micromatch';
-import {cpus}                                                        from 'os';
+import os                                                            from 'os';
 import pLimit                                                        from 'p-limit';
 import {Writable}                                                    from 'stream';
 import {WriteStream}                                                 from 'tty';
 import * as t                                                        from 'typanion';
 
+function availableParallelism() {
+  // TODO: Use os.availableParallelism directly when dropping support for Node.js < 19.4.0
+  if (`availableParallelism` in os)
+    // @ts-expect-error - No types yet
+    return os.availableParallelism();
+
+  return Math.max(1, os.cpus().length);
+}
+
 // eslint-disable-next-line arca/no-default-export
 export default class WorkspacesForeachCommand extends BaseCommand {
   static paths = [
@@ -200,7 +209,7 @@ export default class WorkspacesForeachCommand extends BaseCommand {
     const concurrency = this.parallel ?
       (this.jobs === `unlimited`
         ? Infinity
-        : Number(this.jobs) || Math.max(1, cpus().length / 2))
+        : Number(this.jobs) || Math.ceil(availableParallelism() / 2))
       : 1;
 
     // No need to parallelize if we were explicitly asked for one job

packages/yarnpkg-core/sources/WorkerPool.ts

@@ -1,4 +1,4 @@
-import {cpus}   from 'os';
+import os       from 'os';
 import PLimit   from 'p-limit';
 import {Worker} from 'worker_threads';
 
@@ -8,9 +8,18 @@ type PoolWorker<TOut> = Worker & {
   [kTaskInfo]: null | { resolve: (value: TOut) => void, reject: (reason?: any) => void };
 };
 
+function availableParallelism(): number {
+  // TODO: Use os.availableParallelism directly when dropping support for Node.js < 19.4.0
+  if (`availableParallelism` in os)
+    // @ts-expect-error - No types yet
+    return os.availableParallelism();
+
+  return Math.max(1, os.cpus().length);
+}
+
 export class WorkerPool<TIn, TOut> {
   private workers: Array<PoolWorker<TOut>> = [];
-  private limit = PLimit(Math.max(1, cpus().length));
+  private limit = PLimit(availableParallelism());
   private cleanupInterval: ReturnType<typeof setInterval>;
 
   constructor(private source: string) {