Bukkit Runnable Running Multiple Times

I'm trying to make a runnable where a monster does special abilities every few seconds, however for some reason, this always causes problems.

Whenever two instances of the runnable are running at the same time, the second runnable always speeds up considerably. For example, a few seconds into the Runnable, it will run the " invincibleMessage(instancenumber);" method, even though that should only run after 29 seconds. Anyone know why this is happening?

Code:

public class CryptBossRunnable extends BukkitRunnable {
    private static InstanceMain plugin;
    private int instancenumber;
    private int time;
 
    public CryptBossRunnable(InstanceMain instance){
        plugin = instance;
    }
   
    public CryptBossRunnable(int number, Plugin pl, int thistime){
          instancenumber = number;
          time = thistime;
          }
     
    public void runTask(String name, int number){
        CryptBossRunnable task = new CryptBossRunnable(number, plugin, 0);
        task.runTaskTimer(plugin, 0L, 20L);
    }
   
    @Override
    public void run() {
        if(time == 1){
            messageOne(instancenumber);
        }
        else if(time == 3){
            removeFinalWall(instancenumber);
        }
        else if(time == 6){
            messageTwo(instancenumber);
        }
        else if(time == 8){
            if(plugin.cmm.getBoss(instancenumber) != null){
               
            }else{
            plugin.cmm.spawnBoss(instancenumber);
            }
        }
        if(time > 8){
            if(plugin.cmm.getBoss(instancenumber) != null){
                if(plugin.cmm.getBoss(instancenumber).isDead()){
                    this.cancel();
                    return;
                }
            }
        }
        if(time > 9){
            adjustBar(instancenumber);
        }
        if(time == 1){
            if(instancenumber == 1){
                if(plugin.ia.Crypt1Boss == false){
                    plugin.ia.Crypt1Boss = true;
                }
                else{
                    this.cancel();
                }
            }
            else if(instancenumber == 2){
                if(plugin.ia.Crypt2Boss == false){
                    plugin.ia.Crypt2Boss = true;
                }
                else{
                    this.cancel();
                }
            }
            else if(instancenumber == 3){
                if(plugin.ia.Crypt3Boss == false){
                    plugin.ia.Crypt3Boss = true;
                }
                else{
                    this.cancel();
                }
            }
        }
        if(plugin.cmm.getBoss(instancenumber) != null){
        if(time == 10){
            setTarget(instancenumber);
        }
        if(time > 10){
            plugin.cmm.getBoss(instancenumber).setFireTicks(0);
        }
        if(time % 18 == 0 && time > 17){
            List<Entity> nearbyEnts = plugin.cmm.getBoss(instancenumber).getNearbyEntities(3, 2, 3);
            spinMessage(instancenumber);
            for(Entity ent : nearbyEnts){
                if(ent instanceof Player){
                    ((Player) ent).damage(4, plugin.cmm.getBoss(instancenumber));
                    ent.getWorld().playEffect(ent.getLocation(), Effect.MOBSPAWNER_FLAMES, 1);
                    ent.getWorld().playSound(ent.getLocation(), Sound.ENDERMAN_SCREAM, 1, 1);
                }
            }
        }
        else if(time % 29 == 0){
            invincibleMessage(instancenumber);
            plugin.cmm.getBoss(instancenumber).addPotionEffect(new PotionEffect(PotionEffectType.DAMAGE_RESISTANCE, 100, 5));
            plugin.cmm.getBoss(instancenumber).getWorld().playEffect(plugin.cmm.getBoss(instancenumber).getLocation(), Effect.POTION_BREAK, 1);
            plugin.cmm.getBoss(instancenumber).getWorld().playEffect(plugin.cmm.getBoss(instancenumber).getLocation(), Effect.POTION_BREAK, 1);
        }
        else if(time % 33 == 0){
            int x = 670;
            int y = 4;
            int z = 555;
            Location teleport = new Location(plugin.cmm.getBoss(instancenumber).getWorld(), x, y, z);
            plugin.cmm.getBoss(instancenumber).teleport(teleport);
            plugin.cmm.getBoss(instancenumber).getWorld().playSound(plugin.cmm.getBoss(instancenumber).getLocation(), Sound.ENDERMAN_TELEPORT, 1, 1);
            teleportMessage(instancenumber);
        }
        else if(time % 45 == 0){
            spawnDeadMessage(instancenumber);
            plugin.cmm.getBoss(instancenumber).getWorld().playSound(plugin.cmm.getBoss(instancenumber).getLocation(), Sound.ENDERDRAGON_GROWL, 1, 1);
            plugin.cmm.getBoss(instancenumber).getWorld().spawnEntity(new Location(plugin.cmm.getBoss(instancenumber).getWorld(), 671.5, 4, 563.5), EntityType.ZOMBIE);
            plugin.cmm.getBoss(instancenumber).getWorld().spawnEntity(new Location(plugin.cmm.getBoss(instancenumber).getWorld(), 669.5, 4, 563.5), EntityType.ZOMBIE);
           
            plugin.cmm.getBoss(instancenumber).getWorld().playEffect(new Location(plugin.cmm.getBoss(instancenumber).getWorld(), 671.5, 4, 563.5), Effect.POTION_BREAK, 8);
            plugin.cmm.getBoss(instancenumber).getWorld().playEffect(new Location(plugin.cmm.getBoss(instancenumber).getWorld(), 669.5, 4, 563.5), Effect.POTION_BREAK, 8);
           
            plugin.cmm.getBoss(instancenumber).getWorld().spawnEntity(new Location(plugin.cmm.getBoss(instancenumber).getWorld(), 671.5, 4, 546.5), EntityType.ZOMBIE);
            plugin.cmm.getBoss(instancenumber).getWorld().spawnEntity(new Location(plugin.cmm.getBoss(instancenumber).getWorld(), 669.5, 4, 546.5), EntityType.ZOMBIE);
           
            plugin.cmm.getBoss(instancenumber).getWorld().playEffect(new Location(plugin.cmm.getBoss(instancenumber).getWorld(), 671.5, 4, 546.5), Effect.POTION_BREAK, 8);
            plugin.cmm.getBoss(instancenumber).getWorld().playEffect(new Location(plugin.cmm.getBoss(instancenumber).getWorld(), 669.5, 4, 546.5), Effect.POTION_BREAK, 8);
           
        }
        else if(time % 36 == 0){
            damageIncreaseMessage(instancenumber);
            plugin.cmm.getBoss(instancenumber).addPotionEffect(new PotionEffect(PotionEffectType.INCREASE_DAMAGE, 120, 1));
            plugin.cmm.getBoss(instancenumber).addPotionEffect(new PotionEffect(PotionEffectType.SPEED, 240, 0));
            plugin.cmm.getBoss(instancenumber).getWorld().playEffect(plugin.cmm.getBoss(instancenumber).getLocation(), Effect.POTION_BREAK, 4);
            plugin.cmm.getBoss(instancenumber).getWorld().playEffect(plugin.cmm.getBoss(instancenumber).getLocation(), Effect.POTION_BREAK, 4);
        }
        else if(time % 55 == 0){
            invisibleMessage(instancenumber);
            plugin.cmm.getBoss(instancenumber).addPotionEffect(new PotionEffect(PotionEffectType.INVISIBILITY, 200, 0));
            plugin.cmm.getBoss(instancenumber).getWorld().playSound(plugin.cmm.getBoss(instancenumber).getLocation(), Sound.ENDERDRAGON_HIT, 1, 1);
        }
        else if(time % 52 == 0){
            regenerateMessage(instancenumber);
            if(plugin.cmm.getBoss(instancenumber).getHealth() != plugin.cmm.getBoss(instancenumber).getHealth()){
                plugin.cmm.getBoss(instancenumber).setHealth(plugin.cmm.getBoss(instancenumber).getHealth() + 25);
                plugin.cmm.getBoss(instancenumber).getWorld().playEffect(plugin.cmm.getBoss(instancenumber).getLocation(), Effect.POTION_BREAK, 9);
                plugin.cmm.getBoss(instancenumber).getWorld().playEffect(plugin.cmm.getBoss(instancenumber).getLocation(), Effect.POTION_BREAK, 9);
                plugin.cmm.getBoss(instancenumber).getWorld().playEffect(plugin.cmm.getBoss(instancenumber).getLocation(), Effect.POTION_BREAK, 9);
            }
        }
        }
        time++;
    }

 

hm, maybe you could check if there already is a Runnable happening, for example (this may not work, just an example) :

Code:java

boolean running = false;
 
if (running == false) {
running = true;
new BukkitRunnable() {
@Override
public void run() {
//do stuff
//cancelation logic
running = false;
cancel();
}
}.runTaskTimer(plugin, delay, period