Share a few worker threads with NEWTHREADPOOL()

Total.js 5 · total5@0.0.19 workerthreadpoolperformance Executed against Total.js 5

NEWTHREAD() starts one worker. When many requests need the same heavy job, one worker per request is too many and a single worker makes them wait for each other without any order. NEWTHREADPOOL(name, count, [isfork]) starts count workers of workers/name.js (a thread; with isfork set to true a child process, like NEWFORK()) and hands them out one at a time.

pool.exec(function(worker, release) {}) waits until a worker is free and calls your function with it. Send it the work with worker.postMessage(value), read the answer with worker.once('message', fn) and call release() when you are done: the worker goes back to the pool and the next waiting job takes it.
Without a function, pool.exec() returns a promise that resolves with worker (and the worker has worker.release()), so it works with await.
The jobs are served in the order in which they asked. The pool does not queue the messages of a worker: one job at a time has it.
The pool is also kept in F.workers[name]. pool.workers is the list of the workers.

The worker file is the same as for NEWTHREAD(): NEWTHREAD() inside it returns the handle with worker.message and worker.postMessage(). Here every worker adds up the numbers and says which thread did it.

workers/total.js

require('total5');

const worker = NEWTHREAD();

worker.message = function(message) {
	let total = 0;
	for (let i = 1; i <= message.to; i++)
		total += i;
	worker.postMessage({ to: message.to, total: total, thread: require('worker_threads').threadId });
};

controllers/total.js

exports.install = function() {
	ROUTE('GET /total/{to}/', total);
	ROUTE('GET /await/{to}/', total_await);
	ROUTE('GET /workers/', workers);
};

const pool = NEWTHREADPOOL('total', 2);

function total($) {
	pool.exec(function(worker, release) {
		worker.once('message', function(response) {
			release();
			$.json(response);
		});
		worker.postMessage({ to: +$.params.to });
	});
}

async function total_await($) {
	const worker = await pool.exec();
	worker.once('message', function(response) {
		worker.release();
		$.json(response);
	});
	worker.postMessage({ to: +$.params.to });
}

function workers($) {
	$.json({ workers: pool.workers.length, registered: F.workers.total === pool });
}