[MC-197178] Endermen could get stuck forever if they can't place a block, cluttering the world with unnecessary endermen

Under conditions where endermen are unable to place blocks, they can get stuck forever. This is a serious issue, as it hurts the performance by filling the world with endermen. Here are most of the conditions in which an enderman will get stuck forever:

Endermen holding anything can get stuck above the Nether's ceiling forever, as they cannot place blocks on bedrock
Endermen holding anything can get stuck forever, if they pick up a block and get trapped in a place where there's no valid position to place a block
Endermen holding crimson/warped roots/fungi can get stuck forever, if they get trapped somewhere in a Nether wastes or basalt deltas.
Endermen holding cactus can get stuck forever if they teleport into a cave with no escape
Endermen holding flowers can get stuck forever if they teleport into a cave with no dirt surfaces or escape

The best way to reproduce this is to set the world border to 128, go into the Nether, reach the ceiling, place tnt floating 1 block above the bedrock (so endermen can't walk on top of it), and spawn endermen. When the endermen pick up the tnt, they will be stuck forever. (note: the world border only serves to confine the endermen within an observable area; it still works without the world border)

Linked issues

duplicates 1

MC-191725 Endermen picking up blocks don't count towards the mob cap, and don't despawn, potentially cluttering up the world with endermen if they cannot place the block down Reopened

Attachments

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Comments 3

galaxy_2alex 2020-08-05T22:37:59Z

Duplicate of MC-191725

gaspoweredpick 2020-08-05T22:57:04Z

It's not actually. MC-191725 says that an intentional feature is not an intentional feature. MC-197178 points out problems with said intentional feature.

Either that or MC-191725 implies that endermen will never despawn after picking up a block, even after placing it back down:

When endermen pick up netherack and other items in the new warped forest biome, they no longer count towards the mob cap, and don't despawn, cluttering the warped forest with endermen.

Because of this, MC-197178 is a separate issue to MC-191725.

galaxy_2alex 2020-08-05T23:23:08Z

The description of MC-191725 was not updated (my fault) to include the fact that endermen that hold a block cannot despawn, which happens when they cannot place the block down. It may have been an issue for longer but was never noticed. I don't believe that endermen don't count towards the mobcap after they place down the block, but more testing may need to be done.

I have changed MC-191725 to better reflect the potential issue at hand.