MC-262351Worldgen deadlock caused by supporting block checks
In 23w18a there was a bug fix for MC-1133. One of the changes made to make this happen can cause a worldgen deadlock under certain conditions.
Essentially what's happening is that when an entity is loaded, it often checks for supporting blocks before their bounding box is updated to match the entity's position.
Since the supporting block check uses this bounding box to determine block collisions, this means that it will require chunks around X=0 and Z=0 to be loaded to perform this check, even if the entity is not actually being loaded there.
If this for any reason happens during world generation, such as a structure loading in with entities, this will cause a deadlock because the generating chunk is asking to load another chunk, but can itself never finish until that other chunk is loaded.
This also is not exclusively an issue with servers that disable spawn chunks from loading.
In vanilla this can be reproduced (although inconsistently) by having this happen during world initialization (preparing spawn area) - before all the spawn chunks have finished loading.
Reproduction steps:
- Create a new world with (for ex.) seed 2374522903531219544
- See how the process gets stuck indefinitely. (This isn't guaranteed to happen every time)
Update
I would like to add that this is not only caused by the bounding box not being updated in time. Even when the bounding box is updated before the check, and matches the correct position, this call still seems to be capable of causing a deadlock, but now because requesting chunks for collision checks seems to require the chunk to be fully loaded, which it will never be. I am not 100% sure how chunk loading works so some of this may not be accurate.
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![[Mojang] Gnembon](../../../data/avatars/users/93709.png){kind=small}
Very ImportantCreated Issue:
Worldgen deadlock caused by supporting block checks.
In 23w18a there was a bug fix for
MC-1133. One of the changes made to make this happen can cause a worldgen deadlock under certain conditions.Essentially what's happening is that when an entity is initialized, it often checks for supporting blocks before their bounding box is updated to match the entity's position.
Since the supporting block check uses this bounding box to determine block collisions, this means that it will require chunks around X=0 and Z=0 to be loaded to perform this check, even if the entity is not actually being loaded there.If this for any reason happens during world generation, such as a structure loading in with entities, this will cause a deadlock because the generating chunk is asking to load another chunk, but can itself never finish until that other chunk is loaded.
This also is not exclusively an issue with servers that disable spawn chunks from loading.
In vanilla this can be reproduced (although inconsistently) by having this happen during world initialization (preparing spawn area) - before all the spawn chunks have finished loading.Reproduction steps:
- Create a new world with (for ex.) seed 2374522903531219544
- See how the process gets stuck indefinitely. (This isn't guaranteed to happen every time)
![[Mod] ampolive](../../../data/avatars/users/18949.svg){kind=small}
Worldgen deadlock caused by supporting block checks.
relates to
In 23w18a there was a bug fix for
MC-1133. One of the changes made to make this happen can cause a worldgen deadlock under certain conditions.Essentially what's happening is that when an entity is
initialized, it often checks for supporting blocks before their bounding box is updated to match the entity's position.
Since the supporting block check uses this bounding box to determine block collisions, this means that it will require chunks around X=0 and Z=0 to be loaded to perform this check, even if the entity is not actually being loaded there.If this for any reason happens during world generation, such as a structure loading in with entities, this will cause a deadlock because the generating chunk is asking to load another chunk, but can itself never finish until that other chunk is loaded.
This also is not exclusively an issue with servers that disable spawn chunks from loading.
In vanilla this can be reproduced (although inconsistently) by having this happen during world initialization (preparing spawn area) - before all the spawn chunks have finished loading.Reproduction steps:
- Create a new world with (for ex.) seed 2374522903531219544
- See how the process gets stuck indefinitely. (This isn't guaranteed to happen every time)
In 23w18a there was a bug fix for
MC-1133. One of the changes made to make this happen can cause a worldgen deadlock under certain conditions.Essentially what's happening is that when an entity is loaded, it often checks for supporting blocks before their bounding box is updated to match the entity's position.
Since the supporting block check uses this bounding box to determine block collisions, this means that it will require chunks around X=0 and Z=0 to be loaded to perform this check, even if the entity is not actually being loaded there.If this for any reason happens during world generation, such as a structure loading in with entities, this will cause a deadlock because the generating chunk is asking to load another chunk, but can itself never finish until that other chunk is loaded.
This also is not exclusively an issue with servers that disable spawn chunks from loading.
In vanilla this can be reproduced (although inconsistently) by having this happen during world initialization (preparing spawn area) - before all the spawn chunks have finished loading.Reproduction steps:
- Create a new world with (for ex.) seed 2374522903531219544
- See how the process gets stuck indefinitely. (This isn't guaranteed to happen every time)
![[Mojang] Moesh](../../../data/avatars/users/10122.svg){kind=small}
In 23w18a there was a bug fix for
MC-1133. One of the changes made to make this happen can cause a worldgen deadlock under certain conditions.Essentially what's happening is that when an entity is loaded, it often checks for supporting blocks before their bounding box is updated to match the entity's position.
Since the supporting block check uses this bounding box to determine block collisions, this means that it will require chunks around X=0 and Z=0 to be loaded to perform this check, even if the entity is not actually being loaded there.If this for any reason happens during world generation, such as a structure loading in with entities, this will cause a deadlock because the generating chunk is asking to load another chunk, but can itself never finish until that other chunk is loaded.
This also is not exclusively an issue with servers that disable spawn chunks from loading.
In vanilla this can be reproduced (although inconsistently) by having this happen during world initialization (preparing spawn area) - before all the spawn chunks have finished loading.Reproduction steps:
- Create a new world with (for ex.) seed 2374522903531219544
- See how the process gets stuck indefinitely. (This isn't guaranteed to happen every time)
Update
I would like to add that this is not only caused by the bounding box not being updated in time. Even when the bounding box is updated before the check, and matches the correct position, this call is still capable of causing a deadlock if an entity spawns near a chunk border and the block collision check exceeds that chunk, requiring multiple chunks to be loaded.
In 23w18a there was a bug fix for
MC-1133. One of the changes made to make this happen can cause a worldgen deadlock under certain conditions.Essentially what's happening is that when an entity is loaded, it often checks for supporting blocks before their bounding box is updated to match the entity's position.
Since the supporting block check uses this bounding box to determine block collisions, this means that it will require chunks around X=0 and Z=0 to be loaded to perform this check, even if the entity is not actually being loaded there.If this for any reason happens during world generation, such as a structure loading in with entities, this will cause a deadlock because the generating chunk is asking to load another chunk, but can itself never finish until that other chunk is loaded.
This also is not exclusively an issue with servers that disable spawn chunks from loading.
In vanilla this can be reproduced (although inconsistently) by having this happen during world initialization (preparing spawn area) - before all the spawn chunks have finished loading.Reproduction steps:
- Create a new world with (for ex.) seed 2374522903531219544
- See how the process gets stuck indefinitely. (This isn't guaranteed to happen every time)
Update
I would like to add that this is not only caused by the bounding box not being updated in time. Even when the bounding box is updated before the check, and matches the correct position, this callisstill capable of causing a deadlockif an entity spawns near a chunk border and the block collision check exceedsthatchunk, requiring multiple chunks to be loaded.In 23w18a there was a bug fix for
MC-1133. One of the changes made to make this happen can cause a worldgen deadlock under certain conditions.Essentially what's happening is that when an entity is loaded, it often checks for supporting blocks before their bounding box is updated to match the entity's position.
Since the supporting block check uses this bounding box to determine block collisions, this means that it will require chunks around X=0 and Z=0 to be loaded to perform this check, even if the entity is not actually being loaded there.If this for any reason happens during world generation, such as a structure loading in with entities, this will cause a deadlock because the generating chunk is asking to load another chunk, but can itself never finish until that other chunk is loaded.
This also is not exclusively an issue with servers that disable spawn chunks from loading.
In vanilla this can be reproduced (although inconsistently) by having this happen during world initialization (preparing spawn area) - before all the spawn chunks have finished loading.Reproduction steps:
- Create a new world with (for ex.) seed 2374522903531219544
- See how the process gets stuck indefinitely. (This isn't guaranteed to happen every time)
Update
I would like to add that this is not only caused by the bounding box not being updated in time. Even when the bounding box is updated before the check, and matches the correct position, this call still seems to be capable of causing a deadlock, but now because requesting chunks for collision checks seems to require the chunk to be fully loaded, which it will never be. I am not 100% sure how chunk loading works so some of this may not be accurate.
relates to
![[Mod] violine1101](../../../data/avatars/users/92858.png){kind=small}
is duplicated by
![[Bot] Piston](../../../data/avatars/users/31202.png){kind=small}
Seems like this could be a case of MC-262351.
Is this MC-262351?
Thank you for your report!
We're tracking this issue in MC-262351, so this ticket is being resolved and linked as a duplicate.
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I was able to reproduce this first time using the provided seed, the game has stalled at 1% for several minutes.
Same as mine when I entered the seed "A dios" or 1893531048.
will changing version fix this issue on my world
same for my world I cannot enter it anymore 22517998171852982