<?php

namespace serverdeathrestarter;

use pocketmine\Thread;

class CheckerThread extends Thread{
    public $lastAlive;
    /** @var number */
    private $timeout;
    public function __construct($timeout){
        $this->timeout = $timeout;
    }
    public function run(){
        $this->lastAlive = microtime(true);
        while(true){
            $time = microtime(true);
            if($time - $this->lastAlive > $this->timeout){
                die("Main thread timeout ($this->timeout second(s))");
            }
            sleep(1);
        }
    }
}





=====================================================


<?php

namespace serverdeathrestarter;

use pocketmine\command\Command;
use pocketmine\command\CommandSender;
use pocketmine\plugin\PluginBase;

class SDRPlugin extends PluginBase{
    public function onEnable(){
        $this->saveDefaultConfig();
        $thread = new CheckerThread($this->getConfig()->get("timeout"));
        $thread->start();
    }
    public function onCommand(CommandSender $sender, Command $cmd, $alias, array $args){
        if($cmd->getName() === "serverdie"){
            die;
        }
        if($cmd->getName() === "suspend"){
            $this->suspendThread();
        }
    }
    /**
     * Function for testing
     */
    public static function suspendThread(){
        while(true);
    }
}