feat: expose maxThreads and minThreads out of Piscina instance

src/index.ts

@@ -1030,6 +1030,14 @@ class Piscina extends EventEmitterAsyncResource {
     return this.#pool.destroy();
   }
 
+  get maxThreads (): number {
+    return this.#pool.options.maxThreads;
+  }
+
+  get minThreads (): number {
+    return this.#pool.options.minThreads;
+  }
+
   get options () : FilledOptions {
     return this.#pool.options;
   }

test/post-task.ts

@@ -1,4 +1,5 @@
 import { MessageChannel } from 'worker_threads';
+import { cpus } from 'os';
 import Piscina from '..';
 import { test } from 'tap';
 import { resolve } from 'path';
@@ -131,3 +132,47 @@ test('Piscina.run options is correct type', async ({ rejects }) => {
 
   rejects(pool.run(42, 1 as any), /options must be an object/);
 });
+
+test('Piscina.maxThreads should return the max number of threads to be used (default)', ({ equal, plan }) => {
+  plan(1);
+  const pool = new Piscina({
+    filename: resolve(__dirname, 'fixtures/eval.js')
+  });
+
+  const maxThreads = (cpus().length || 1) * 1.5;
+
+  equal(pool.maxThreads, maxThreads);
+});
+
+test('Piscina.minThreads should return the max number of threads to be used (custom)', ({ equal, plan }) => {
+  const maxThreads = 3;
+  const pool = new Piscina({
+    maxThreads,
+    filename: resolve(__dirname, 'fixtures/eval.js')
+  });
+
+  plan(1);
+
+  equal(pool.maxThreads, maxThreads);
+});
+
+test('Piscina.minThreads should return the max number of threads to be used (default)', ({ equal, plan }) => {
+  const pool = new Piscina({
+    filename: resolve(__dirname, 'fixtures/eval.js')
+  });
+  const minThreads = Math.max((cpus().length || 1) / 2, 1);
+
+  plan(1);
+  equal(pool.minThreads, minThreads);
+});
+
+test('Piscina.minThreads should return the max number of threads to be used (custom)', ({ equal, plan }) => {
+  const minThreads = 2;
+  const pool = new Piscina({
+    filename: resolve(__dirname, 'fixtures/eval.js'),
+    minThreads
+  });
+  plan(1);
+
+  equal(pool.minThreads, minThreads);
+});