Containers next to chunk borders can lose items when upgrading

Cross post from duplicate MC-134205.

I was able to reproduce this issue in several ways and think I got a good hypothesis about what is going on.

MC-134205_4.zip is a world that reproduces the issue of a chest randomly losing its items.
You can open the world in 1.12.2 first to confirm that the chest is filled.
Then open it in 1.13. Only half of the chest should be filled now.
(I used Java 1.8.0_171 64bit, that might matter, as I suspect hash map ordering to play a role here, which changed from Java 1.7 to Java 1.8)

When closing and opening the world again in 1.13 the chest might become invisible until you open it.

MC-134205_3.zip reproduces the issue in a way that may give a better idea how it is caused.

All chests in this world are full with stone.

Load the world in 1.13 for the first time.

Depending on where the chests are, compared to the player, some of them randomly become empty.

To get a feeling on how to reproduce this, you can turn on the command block and then fly around behind the chests.
The command will replace empty chest with glass, so each time it happens a glass block is placed.
So it gives nice visual feedback whenever the issue is happening.

Once I had figured out how to move to make it happen, I put items in one of the glitched chests.
https://www.youtube.com/watch?v=adPGdp4x85E&t=3m25s

As you can see, the chest doesn't just become empty, but it seems to switch with another chests.

So judging from this data, my guess what is going on is, that the recent changes to chests lead to sometimes two tile entities being created on upgrading.
Depending on which one of them updates first, that one is shown to the player.
I recall tile entities being ordered by a hash map, so that could explain the position depended empty chests.

The issue seems to only happen when opening an old map in 1.13 for the first time, but in some cases this means a complete loss of the items in a chest (see MC-134205_3.zip).

I hope this helps to fully track down and fix the issue.
While this issue isn't as severe as the initial tests indicated, I still think it's something worthy of a 1.13.1.

Additional notes:
i) I was not able to reproduce it for other tile entities than chests yet, but several people reported that hopper can become empty too.
ii) The behaviour in MC-134205_4.zip shows that it is not bound to chunk borders, although the chests that automatically got saved empty were at chunk borders so far.

I noticed in testing that the highest and most South or East double chest (south seems favored), with only one side (left or right) at a chunk border, would have contents missing upon opening in 1.13. If there is another chest further South or East within the chunk, with the long side (front or back) not along a chunk border, then the chests contents are not missing.

I opened the

world that @unknown added and switched on the command block. I was able to target on a chest that when opened would switch between half and full. Never replaced with glass though. Although other chests had been replaced with glass after several minutes.  I am using Java 1.8.0_181 64-bit.

Many attempts at this and I noticed that often the game would kick out of the chest inventory GUI. I had the world running in the background with the chest open. Suddenly it paused and went to the Game Menu. The chest was not at a chunk border.

What @unknown has revealed I assume is related, but Is it a different issue that this ticket?

If the world was upgraded from prior to 1.12.2, then MC-79154 would create duplicate block entities, although in my experiments, it was always for only part of a tick. There may be some other bug that saves multiple copies of block entity data with a chunk, perhaps. Upgrading from pre-1.12.2 would need to account for how 1.12.2 had dealt with which duplicate was shown. With chunk borders being involved, MC-119971 and MC-108469 might be related.

After some more digging, I can confirm that more TileEntities get created for double chests on the server side than common sense permits.
Surprisingly in the cases where items get lost right away, that half of the chest does not get loaded from NBT at all, so it might be two issues as @unknown suspected.

I strongly suspect the method bna.E() to play an important role in this.
From what I can tell it's a method in Chunk.java which handles (legacy?) TileEntities on loading.

However it creates three TileEntities for a double chest.

First in bna.E(SourceFile:1125) two TileEntities get created due to bnk.b(SourceFile:151) and bnk.b(SourceFile:153) later in the stack trace.

And then later in bna.E(SourceFile:1168) presumably the chest gets loaded from NBT which creates another TileEntity.

For a double chest that keeps its content on the first loading in 1.13:
ChestTE created (bna.E(SourceFile:1125))
ChestTE created (bna.E(SourceFile:1125))
ChestTE created (bna.E(SourceFile:1168))
ChestTE content loaded (bna.E(SourceFile:1168))
ChestTE created (bna.E(SourceFile:1168))
ChestTE content loaded (bna.E(SourceFile:1168))

For the one in

(losing half the inventory):
ChestTE created (bna.E(SourceFile:1125))
ChestTE created (bna.E(SourceFile:1125))
ChestTE created (bna.E(SourceFile:1168))
ChestTE content loaded (bna.E(SourceFile:1168))

So in the cases where the chest content gets lost right away, it seems like it actually ends up not loading that half of the chest at all for some reason.
However the duplicate creations in the case where it keeps the content are likely not cleaned up properly either, as this could explain the behaviour in

Video.

Summed up interesting methods/lines to start looking for the issue:
bna.E(SourceFile:1125)
bna.E(SourceFile:1168)
bnk.b(SourceFile:151)
bnk.b(SourceFile:153)

Good to know that issue's getting fixed 🙂

I would like to point out that this bug is not fixed.

I placed a bunch of chests on borders of chunks on a 1.12.2 world and then opened it in 1.13.1. While some of them were still full, not all of them were.
I had placed 2 double chests and 1 double trap chest at all 4 borders of 2 adjacent chunks (21 in total, didn't double up in the adjacent border). Some chests within one border were empty while others were not, so the result didn't really seem consistent.

I'm running Ubuntu 18.04.1 LTS and java

java -version
java version "1.8.0_181"
Java(TM) SE Runtime Environment (build 1.8.0_181-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.181-b13, mixed mode)

My test world (in 1.12.2):

https://www.dropbox.com/s/w95vmt3gurf7mdc/creative_test_sp_28_08_2018_1_12%20%281.12%29.zip?dl=0
My test world after converting (in 1.13.1):
https://www.dropbox.com/s/r1a9t415sh61vti/creative_test_sp_28_08_2018_1_12%20%281.13%29.zip?dl=0
 

Thanks Mart!

I can confirm the same issue on my end - several of the chests are only half full in 1.13.1

I was made aware on discord that this is actually a different issue (i.e chests ACROSS chunk borders not NEXT TO them). I initially failed to understand that (even though it is quite clear, especially from the picture provided).

Is there a new 1.13.1 issue already tracked for this? I couldn't find one.

Or should one be made?

I've just ran a few tests using Mart's 1.12.2 test world.

I first loaded/upgraded it in 1.13, where none of the chest contents were wiped.

I then loaded/upgraded it in 1.13.1, where several halves of the double chests were wiped.

I then retried it in both 1.13 and 1.13.1, each yielding the same results as above. (with the exact same chest locations wiped in 1.13.1 as before).

I loaded the un-upgraded version in 1.12.2 and removed the opposite halves of the double chests, which are not wiped in upgrading to 1.13.1, leaving just the single chests which are usually wiped in the upgrade. When loading this in 1.13.1, they were not wiped.

in 1.13.1 a chest lost a half inventory if it stay between 2 chunks (after world convert from 1.12.2)

if a chest on the border from a chunk but inside, that worked now (it was a problem in 1.13.0)

so world convertation is not save in 1.13.1 and need to be fixed

Does this only work for containers that hold items (dispensers, droppers, chests), or does it also work for blocks containing data like command blocks? Also, I know it works for chests, but what about the other containers I mentioned?