pocketmine\scheduler\AsyncPool::increaseSize PHP Method

    public function increaseSize($newSize)
    {
        $newSize = (int) $newSize;
        if ($newSize > $this->size) {
            for ($i = $this->size; $i < $newSize; ++$i) {
                $this->workerUsage[$i] = 0;
                $this->workers[$i] = new AsyncWorker($this->server->getLogger(), $i + 1);
                $this->workers[$i]->setClassLoader($this->server->getLoader());
                $this->workers[$i]->start();
            }
            $this->size = $newSize;
        }
    }

 public function increaseAsyncTaskPoolSize($newSize)
 {
     $this->asyncPool->increaseSize($newSize);
 }