src/Lifo/IPC/ProcessPool.php
public function killAll($signo = SIGTERM)
    {
        foreach ($this->workers as $w) {
            $this->kill($w['pid'], $signo);
        }
        return $this;
    }
public function killAll($signo = SIGTERM)
    {
        foreach ($this->workers as $w) {
            $this->kill($w['pid'], $signo);
        }
        return $this;
    }
Send a SIGTERM (or other) signal to all current workers