Confirmed on 1.8
I personally haven't seen it happen again as I update my snapshots. I currently have my server running on 1.8-pre2 and things are still running smoothly without anymore crashes.
@Anthony Martin I never really saw this issue before but I agree that it seems to be worse in this latest snapshot (14w31a). My server crashed and I believe it was caused by pathfinding threads going crazy. See MC-64662
Is this still an issue as of 14w31a? @Dinnerbone made pathfinding multi-threaded, which might address the performance of it.
Happened to me again. In the same environment as last time. Both the previous time and this time I was simply moving around my world, and it seems as though chunks were still loading as I looked around when the crash occurred. The previous incident was in survival mode with a normally generated world. This instance was in creative mode in a flat desert world.
Affects 14w19a on OS X Mavericks, 64 bit Oracle JVM. Crash report attached.
It seems that signs can cause this error to occur, too. I was able to move my character to the nether where I had no item frames, but when I looked at a sign, the game crashed.
This is definitely happening to me in 14w11b with both chickens and cows (haven't tested with pigs). My chickens have a smaller enclosure (2x2) and die more frequently (during gameplay, probably when chunk gets unloaded then loaded). The cows' enclosure is a larger one (approx 8x15) and they seem to only die when I log back into my world.
I can confirm that this is still a problem in 13w47e. It seems to be that all of the hotkeys and other inventory type shortcuts don't work while mounted on a horse, donkey, or mule.
Attempted to reproduce in 1.6.1 in Creative Mode. Spawned a horse with an egg, tamed it, put a name on a name tag, then applied it to the horse. After the horse had the name from the tag, logged out, then logged back in. The horse was still there. Problem didn't appear to exist.
I've found that I can get a converted 32x texture pack to work on the first load without distorting the fonts. However, after closing and re-opening MineCraft, the glitch shows up again, even with the default pack. The workaround for me has been to delete any resource packs found in the resource pack folder before opening MineCraft, then copy over the converted hi-res pack to the proper folder, then select it within MineCraft, and it works just fine.
Because of this behavior I'm questioning what Grum has said about this not being a bug, since the hi-res fonts do in fact work after jumping through some hoops.
My guess is the problem is related to rounding errors and/or the hit box of the mobs.
Probably what happens is their location gets saved with a very precise floating point number and then when the chunk they're in gets re-loaded, that number gets rounded to something less precise and the mob is moved and they end up in a solid block or on the other side of a fence. The other thing could be that their hit box overlaps with other mobs and there's some sort of algorithm which attempts to keep all mobs a certain distance apart and their location is put to one of those unfavorable locations. The problem could also be a problem of those two things.
Just my two cents.