I made a AI (goal) that zombie break block.

To show the block breaking, I used `destroyBlockProgress` with reference to `BreakDoorGoal`.

It's fine when there's just one or two zombies, but when I summon multiple zombies, it crashes after a few minutes.

crash log: https://gist.github.com/reasure3/9ec90ab2141968535630c5d72558de79

simple code:

public class SetOrBreakBlockGoal extends Goal {
    protected PathfinderMob mob;
    protected LivingEntity target;
    protected Action action;
    protected int blockInteractTime;
    protected int breakTime;
    protected int lastProgress;
    protected BlockState block;
    protected BlockPos.MutableBlockPos blockPos;  <-- This was a problem. not use MutableBlockPos!!
    protected long lastStuckCheckTime;
    protected Vec3 lastStuckCheckPos;
    protected boolean isStuck;

    public SetOrBreakBlockGoal(PathfinderMob mob) {
        this.mob = mob;
        this.action = Action.NONE;
        this.blockInteractTime = -1;
        this.blockPos = new BlockPos.MutableBlockPos(0, 0, 0);
        this.lastProgress = -1;
        this.lastStuckCheckTime = mob.level.getGameTime();
        this.lastStuckCheckPos = Vec3.ZERO;
        this.isStuck = false;
    }

    @Override
    public boolean canUse() {
        if (mob.level instanceof ServerLevel level) {
            if (MathUtil.getDay(level) >= SpawnConfig.ZOMBIE_SET_OR_BREAK_BLOCLK_DAY.get()) {
                target = mob.getTarget();
                if (!isRightTarget()) return false;
                checkStuck();
                return isStuck;
            }
        }
        return false;
    }

    @Override
    public boolean canContinueToUse() {
        if (action == Action.NONE) return false;
        if (blockInteractTime < 0) return false;
        if (isRightTarget()) {
            return mob.level.getBlockState(blockPos).is(block.getBlock());
        }
        return false;
    }

    @Override
    public void start() {
        int dy = target.getBlockY() - mob.getBlockY();
        if (dy > 1) {
            blockPos.set(mob.getBlockX(), mob.getBlockY() + 2, mob.getBlockZ());
            block = mob.level.getBlockState(blockPos);
            if (block.isAir()) {
                // set block code
            } else {
                block = mob.level.getBlockState(blockPos);
                breakTime = getBlockBreakTick();
               blockInteractTime = breakTime;
               if (breakTime == 0) action = Action.BREAK_INSTANCE;
               else if (breakTime < 0) action = Action.NONE;
               else action = Action.BREAK;
            }
        } else action == Action.NONE;
      
        if (action == Action.BREAK && !ForgeHooks.canEntityDestroy(mob.level, blockPos, mob)) {
            action = Action.NONE;
        }
    }

    @Override
    public void tick() {
        if (action == Action.BREAK) {
            if (mob.level.random.nextInt(10) == 0 && !mob.swinging) {
                mob.swing(mob.getUsedItemHand());
            }
            // breaking block
            int progress = (int) ((float) (breakTime - blockInteractTime) / (float) breakTime * 10.0f);
            if (progress != lastProgress) {
                mob.level.destroyBlockProgress(mob.getId(), blockPos, progress);
                lastProgress = progress;
            }
        }
        // goal is finished
        if (blockInteractTime == 0) {
            if (action == Action.BREAK_INSTANCE || action == Action.BREAK) {
                block = mob.level.getBlockState(blockPos);
                BlockEntity blockEntity = block.hasBlockEntity() ? mob.level.getBlockEntity(blockPos) : null;
                mob.level.removeBlock(blockPos, false);
                // this.mob.level.levelEvent(1021, blockPos, 0);
                this.mob.level.levelEvent(2001, blockPos, Block.getId(mob.level.getBlockState(blockPos)));
                Block.dropResources(block, mob.level, blockPos, blockEntity, mob, mob.getMainHandItem());
            } 
        }
        blockInteractTime--;
    }

    @Override
    public void stop() {
        if (action == Action.BREAK)
           mob.level.destroyBlockProgress(mob.getId(), blockPos, -1);
        action = Action.NONE;
        blockInteractTime = -1;
        lastProgress = -1;
        isStuck = false;
        lastStuckCheckTime = mob.level.getGameTime();
        lastStuckCheckPos = mob.position();
    }
}

full code: https://github.com/reasure3/ZombieSurvivalMod/blob/master/src/main/java/com/reasure/zomsurvival/entity/goal/SetOrBreakBlockGoal.java

Edited January 4, 20232 yr by reasure3

A number of cases seem to occur if the block is fluid.
Is there any correct way to check that a block is fluid?

Crash occurs even when the block is a flat block (dirt, sand, etc.).

Edited January 4, 20232 yr by reasure3

I know the cause. It is solved by using BlockPos instead of MutableBlockPos. I thought it wouldn't matter because it was packet communication from the server to the client, but it seems to be different in single player.