Animal Suffocation Bug Info Thread

[FlowerChild]

With the recent changes I made to prevent animal spawning, keeping your animals alive is now obviously a much bigger deal, and thus having them die from random bugs is a much bigger deal.

I wanted to create this thread for people to provide info on when they find it happens, in order to help me narrow it down and hopefully fix it. If you have links to any related threads elsewhere on this issue, that would be helpful as well.

[Padfoote]

When this happens to me in SSP it'll happen right when I log on, or rarely when returning from the Nether. Also in SMP, I've noticed it happens when someone gets on the server after a restart, or after a period of time when nobody was on. In both SSP and SMP, I have seen it happen when returning to base after heading out a few thousand blocks.

Hope this helps.

[FlowerChild]

Yup, I'm already aware it tends to happen on chunk load (I probably should have mentioned that in the OP). I think what I'd like to get a better idea of is if it is specific to particular kinds of surrounding blocks and that kind of thing, as I've never actually observed it myself.

Also worth noting: I know that there are synchronization bugs between client and server that will cause animals to *appear* to drop through the floor or whatever, but reloading will generally get them to appear where they're supposed to be.

That's a separate issue IMO (and I know it's related to rounding errors between the client and server), and shouldn't affect the health of animals since it's the server that determines whether they take damage or not.

So yeah, I'm specifically looking for info as to what kind of circumstances they actually suffocate under.

[FlowerChild]

Oh, if people have screenshots of areas in which they've seen animals suffocate, that would be awesomesauce. If you also know where it happened within the screenshot and can circle the location, that would be extra gooey awesomesauce.

[Oswarlan]

This spot in my soon to be renovated animal farm has claimed its fair share of baby cows.

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The part with the 2 fences above cobble. I haven't had adult cows die here probably due to the fence being a non-solid block and them being able to "breathe" and move back out. Didn't circle since it is directly what I am looking at here. Sorry.

Flowerchild, you mentioned that the de-synch causes them to only visually drop through the ground, but this farm in my picture actually has let a fair number of cows and sheep through the floor, the actual cow, not a visual bug. It is only one block thick, with a floor underneath, if that matters.


Edit: Cows are evil. They seem to push each other into walls now. Kind of nulls my theory about the above spot, as it looks like the cow is mostly in the glass pane?

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[Niyu]

Pics in spoiler

You can see the cow drops where the cow died.

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And this is the other side of the wall

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[Stormweaver]

I notice it most often when a number of mobs (in most recent cases, chickens) are in a crowded space with water pushing them towards a solid block. In all observed cases, only one or two chickens (normally of at least 16 in a 3 bock wide water flow) actually glitch into the block.

I've never seen it happen to just one mob on it's own on solid ground, even if fully enclosed.

[FlowerChild]

Ah...thanks Storm. It would make sense if this were due to overcrowding and the collision resolution code pushing animals through blocks in an attempt to resolve it.

Might also make sense why I haven't seen much of it myself, as I tend not to overcrowd like that.

[Tsugumi Henduluin]

I have a small 9x9 enclosed space in my base that serves as a temporary chicken farm of sorts. Every now and then when I come back from an expedition to a place reasonably far away from my base (couple hundred blocks) or down in my mines, I tend to find a chicken or two dead. Never could figure out what caused it, though I had never heard of this bug until now.
I've noticed that chickens tend to huddle up in the corner of the room, which is also where I tend to find their drops. My suspicion is that they push each other into the wall somehow. I'm afraid I don't have a screenshot of a dead chicken right now, but I'll keep in mind to make one if it happens again.
The enclosure is made out of natural stone on two of the sides and planks on the other two, with a 1x2 hole that has a fence gate for a door.

At any given moment there are only at most 20-odd chickens running around in there, but I suspect their hugging the corners might make the problem worse.

[FlowerChild]

Actually, that gives me a thought: if this tends to occur on chunk load, AND it tends to occur when animals are crowded, it makes me think that perhaps animals are trying to resolve collisions before the surrounding blocks are actually loaded, thus, they're getting pushed into "empty" areas, then have blocks loaded on top of them causing them to suffocate.

Just a theory, but I think that will be the first area I investigate.

[FlowerChild]

Oh ho...wait...even better:

Maybe they're being pushed into neighboring chunks which aren't loaded yet?

Can some of you guys that are experiencing this check the distance to chunk boundary on where this tends to occur?

[Oswarlan]

For my first screenshot above it is 0 on the far fence, and 1 on the close fence, and for the second screenshot it is 2 at the wooden block before the panes, and goes down by one each block further. Hope it helps.

[Tsugumi Henduluin]

You might be on to something there. The one corner where I most often see drops lie about, is only 1 block away from a boundary. The others are anywhere between 3-6 blocks away.
Now I must admit I have seen feathers in other locations, but relatively close by. It might be possible the chickens clip through some nearby blocks before dying, but as I have never actually seen it happen while present, I cannot be sure.

[Equitis1024]

I don't know if this is helpful, but I've observed that if a baby animal is being pushed against a wall (often by other babies trying to get to an out-of-reach parent) it will often glitch into that wall as it turns into an adult. If the wall is made of solid blocks the adult will usually suffocate. If the wall is transparent then the adult often walks out the other side.

[Ethazeriel]

I don't know if this is helpful, but I've observed that if a baby animal is being pushed against a wall (often by other babies trying to get to an out-of-reach parent) it will often glitch into that wall as it turns into an adult. If the wall is made of solid blocks the adult will usually suffocate. If the wall is transparent then the adult often walks out the other side.

This happens to my chickens regularly. I've often found the remains of dead chickens in my farm, but only recently did I witness this happening. A baby was pressed up against a solid, 1 block high wall. Something happened (presumably the transformation into an adult), and the chicken died. It was a bit of an "aha" moment for me, although there isn't anything I can do to prevent it. My chicken farm:

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Dead chicken:

[ExpHP]

Well, I was expecting to be able to provide counter-evidence to the collision/chunk boundary theory based on previous experience with animals escaping from fence enclosures, but...

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The lines are chunk boundaries.

This is the only place I've had suffocation recently. It occurred while I was on a journey, there were 3 animals, and, as you can see, it was near a chunk boundary.

[piter_50]

I was playing in SSP, trying to lead 2 chickens up a hill to my base. What basically what happened was one chicken glitched into the earth and was stuck 1 block down. I could not get it out of the dirt. Not by digging, not even going into water and coming back out could bring it back to surface. I happened to log in and out where it was stuck and when i came back on, chicken parts were all that were left.

I had a similar issue leading a single chicken up a hill and the same thing happened. It got stuck in the dirt. Trying to dig it out lead to it just dropping one level further underground.

I will have to check for chunk boundaries, its on my other laptop at home.

[FlowerChild]

I had a similar issue leading a single chicken up a hill and the same thing happened. It got stuck in the dirt. Trying to dig it out lead to it just dropping one level further underground.

That's likely the other issue I mentioned with client/server desync.

[ItchyFlea]

I've had baby chickens suffocate upon transformation into adults in the middle of the chicken coup. The dragon orb is where the chicken was standing when it suffocated.

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As for overcrowding, it definitely does cause animals to push others into solid blocks. There is something to do with chunk load, as the cows only get stuck like this when the chunk gets loaded. However the fence I'm looking at is 3 blocks away from a chunk border.
If it helps I've never had a cow die of suffocation with this type of pen design, nor have I had any escapees.

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[Thalarctia]

*snip*

The reason you haven't had cow deaths is because their head is in the fence block, which is considered transparent. Since creatures in Minecraft don't breathe air, but light, you cannot suffocate in transparent blocks :)

Since glass is one of the only full, transparent blocks, they are also a very good material for building pens out of, to prevent these kind of suffocation glitches. Would even work for the floor one, although its a rather meta-gamey solution to a very real problem.

[FlowerChild]

As for overcrowding, it definitely does cause animals to push others into solid blocks. There is something to do with chunk load, as the cows only get stuck like this when the chunk gets loaded. However the fence I'm looking at is 3 blocks away from a chunk border.
If it helps I've never had a cow die of suffocation with this type of pen design, nor have I had any escapees.

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If that's seriously a pen in your world, I'd consider not crowding animals to that degree. You're basically creating a situation in which the number of collisions that try to be resolved (unsuccessfully) per tick increases geometrically with each overlapping animal, similar to what happens with quantum chicken builds, and that's going to suck on your performance like crazy.

While I want to try and resolve this bug, I definitely won't be taking it to the extent where I try to fix situations like the one you have pictured, as it's really just pushing things to a retarded level. I'd personally prefer to kill animals that are forced into that kind of situation, but have refrained from doing so due to potential damage to existing builds.

[myrkana]

well heres some more feedback if you need it: we had cows inside out home made of stone bricks, logged off for the night and when I came back most had suffocated :/ I had 6 or so babies left and when I logged out again all but 2 disappeared >...>

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Where i am standing is the corner of the room, right at a chunk boundary. I moved my sheep to a basement room with fences placed on the walls and they haven't suffocated since i put them down there, though one is stuck in the corner of the fences :-p

[ion]

the move to 1.5 made most of the bugs more obvious. while in 1.4.5 mobs didn't get pushed into full blocks now they get into them when they grow up and at chunk load.
in 1.4.5 a wooden fence pen would keep all mobs inside it no matter the amount of them ( tested with cows), now is more that it doesn't exists the pen after few trips back and forth.
coblestone walls make the glitching possible at the corners and at the connection with a full block in 1.4.5. animals didn't get suffocation damage but just were teleported to an empthy block near the pen, now they just get killed into a full block.
and off course grum said that it can't be solved :)

[Vexalor]

If it's any help, I've never experienced any occurrence of one of these suffocation bugs, and I just checked and none of my animal pens are near a chunk boundary. Further, I generally don't crowd my animals. I have a very large population of animals, and it seems these two practices, one incidental, the other intentional, have entirely protected me from this bug.

Also, I mentioned this at some point in the Vanilla News thread, but, with the arrival of 1.5/1.5.1, Mojang has experienced a very large increase in animal/collision box related bugs. I'm not sure if this has had anything to do with what Dinnerbone modified (rail avoidance code, etc.), but it may be more than just the increasing value of animals in BTW that is causing a large number of people to suddenly take interest in this issue.

[Zhil]

I've seen the bug happen with two cows in a 10x10 pen. This was in 1.2.5, so I'm not sure if it's still the same ruleset. Now that you mention it, the cows did always glitch out through the same side of the pen, so that side being on a chunk boundary is very plausible.