Put the summary of the bug you're having here

What I expected to happen was...:
Normally I would expect a moderate amount of mobs spawning at night.

What actually happened was...:
Every available space surrounding my established base is filled with either spiders or skeletons. As I stand atop my building, every outside space is filled with either skeletons or spiders. They have not spawned in the lighted areas in my "house". But the game is struggling with the amount of mobs spawned.

Steps to Reproduce:
1. Unknown. The bud occurred when I loaded the game.