synchronized void unlockContext(int x, int z)
    {
        for (int xx = 0; xx < 3; xx++)
            for (int zz = 0; zz < 3; zz++)
            {
                Chunk c = getChunk(x + xx - 1, z + zz - 1);
                if (c != null)
                    c.opLock.unlock();
            }
        taskQueue.addAll(lockedTasksQueue);
        lockedTasksQueue.clear();
    }