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Use availableParallelism, not cpus().length when determining max workers #569

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Use availableParallelism, not cpus().length when determining max workers #569

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4990e94
Use availableParallelism for determining maxWorkers
bdurette Jul 23, 2026
268f9f4
Update tests to reflect change to using parallelism
bdurette Jul 23, 2026
ca7a864
Remove fallback to cpus.
bdurette Jul 23, 2026
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2 changes: 1 addition & 1 deletion src/environment.js
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Original file line number Diff line number Diff line change
Expand Up @@ -26,5 +26,5 @@ module.exports.isMainThread = module.exports.platform === 'node'
// determines the number of cpus available
module.exports.cpus = module.exports.platform === 'browser'
? self.navigator.hardwareConcurrency
: require('os').cpus().length;
: require('os').availableParallelism();

18 changes: 9 additions & 9 deletions test/Pool.test.js
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Expand Up @@ -885,11 +885,11 @@ describe('Pool', function () {
});
});

it('should take number of cpus minus one as default maxWorkers', function () {
it('should take the available parallelism minus one as default maxWorkers', function () {
var pool = createPool();

var cpus = require('os').cpus();
assert.strictEqual(pool.maxWorkers, cpus.length - 1);
var parallelism = require('os').availableParallelism();
assert.strictEqual(pool.maxWorkers, parallelism - 1);

return pool.terminate();
});
Expand All @@ -908,19 +908,19 @@ describe('Pool', function () {
}, TypeError);
});

it('should create number of cpus minus one when minWorkers set to \'max\'', function () {
it('should create available parallelism minus one when minWorkers set to \'max\'', function () {
var pool = createPool({minWorkers:'max'});

var cpus = require('os').cpus();
assert.strictEqual(pool.workers.length, cpus.length - 1);
var parallelism = require('os').availableParallelism();
assert.strictEqual(pool.workers.length, parallelism - 1);

return pool.terminate();
});

it('should increase maxWorkers to match minWorkers', function () {
var cpus = require('os').cpus();
var count = cpus.length + 2;
var tasksCount = cpus.length * 2;
var parallelism = require('os').availableParallelism();
var count = parallelism + 2;
var tasksCount = parallelism * 2;
var pool = createPool({minWorkers: count});

var tasks = []
Expand Down