class Semaphore {

  constructor(max) {

    this.max = max;

    this.available = max;

    this.waiting = [];

  }

​

  async acquire() {

    return new Promise((resolve) => {

      if (this.available > 0) {

        this.available--;

        resolve();

      } else {

        this.waiting.push(resolve);

      }

    });

  }

​

  release() {

    if (this.waiting.length > 0) {

      const resolve = this.waiting.shift();

      resolve();

    } else {

      this.available++;

    }

  }

}

​

​

const semaphore = new Semaphore(2); // Maksimum 2 tugas simultan

​

async function task(i) {

  await semaphore.acquire();

  console.log(`Task ${i} started`);

  // Simulasi tugas berat

  await new Promise(resolve => setTimeout(resolve, 1000));

  console.log(`Task ${i} finished`);

  semaphore.release();

}

​

for (let i = 0; i < 5; i++) {

  task(i);

}