[NeoForge 1.21.1] Server thread hangs when creating new world in large modpack

unilock commented

2026-03-06 21:43:24 +00:00

With Menderman installed, the game freezes for an indefinite amount of time when generating a new world. This is in a particularly large NeoForge 1.21.1 modpack, so it's likely related to some other mod, but the limited amount of debugging information makes it difficult to narrow down. Attached are a thread dump from jstack and the latest.log file.

With Menderman installed, the game freezes for an indefinite amount of time when generating a new world. This is in a particularly large NeoForge 1.21.1 modpack, so it's likely related to some other mod, but the limited amount of debugging information makes it difficult to narrow down. Attached are a thread dump from `jstack` and the `latest.log` file.

jstack_14312.txt

68 KiB

latest.log

848 KiB

Cow commented

2026-03-07 06:19:25 +00:00

Owner

Something is very wrong here. It is a difficult task to narrow down.

Somehow some of my component generation logic is recursing when it shouldn't be.

Something is **very** wrong here. It is a difficult task to narrow down. Somehow some of my component generation logic is recursing when it shouldn't be.

Cow commented

2026-03-07 06:19:51 +00:00

Owner

Could I have your full mod list? I want to see if there are any standouts in the crowd.

unilock commented

2026-03-07 14:14:19 +00:00

Author

I've discovered that the game does eventually load, it just takes a little while...

[09:10:24] [Render thread/WARN] [ModernFix/]: Time from main menu to in-game was 952.9085 seconds

(this was with a logger added to print the name of every item as the registry was iterated through in MendermanDefaultComponents#createFallbackRepairRequirements (in case it was getting stuck on one in particular), so the load time in practice may be slightly less)

Attached is a manually triggered crash report that should contain my full list of mods.

EDIT: Without the debugging log messages:

[09Mar2026 13:30:32.071] [Render thread/WARN] [ModernFix/]: Time from main menu to in-game was 467.1204 seconds

I've discovered that the game *does* eventually load, it just takes a little while... ``` [09:10:24] [Render thread/WARN] [ModernFix/]: Time from main menu to in-game was 952.9085 seconds ``` (this was with a logger added to print the name of every item as the registry was iterated through in `MendermanDefaultComponents#createFallbackRepairRequirements` (in case it was getting stuck on one in particular), so the load time in practice may be slightly less) Attached is a manually triggered crash report that should contain my full list of mods. EDIT: Without the debugging log messages: ``` [09Mar2026 13:30:32.071] [Render thread/WARN] [ModernFix/]: Time from main menu to in-game was 467.1204 seconds ```

crash-2026-03-07_09.13.22-client.txt

242 KiB

👍 1

unilock commented

2026-03-17 21:54:32 +00:00

Author

Adding if (!defaultInstance.isDamageableItem()) continue; before the getRepairItems(Item)List call reduces the world load time significantly:

[17:50:42] [Render thread/WARN] [ModernFix/]: Time from main menu to in-game was 101.78393 seconds

Adding `if (!defaultInstance.isDamageableItem()) continue;` before the `getRepairItems(Item)List` call reduces the world load time significantly: ``` [17:50:42] [Render thread/WARN] [ModernFix/]: Time from main menu to in-game was 101.78393 seconds ```

👍 1

Cow commented

2026-03-18 00:16:22 +00:00

Owner

@unilock wrote in #3 (comment):

Adding if (!defaultInstance.isDamageableItem()) continue; before the getRepairItems(Item)List call reduces the world load time significantly:
[17:50:42] [Render thread/WARN] [ModernFix/]: Time from main menu to in-game was 101.78393 seconds

Oh! Awesome! Thanks for investigating. I'll do exactly that as soon as I get to updating.

@unilock wrote in https://git.greenhouse.lgbt/Modding/menderman/issues/3#issuecomment-447: > Adding `if (!defaultInstance.isDamageableItem()) continue;` before the `getRepairItems(Item)List` call reduces the world load time significantly: > > ```text > [17:50:42] [Render thread/WARN] [ModernFix/]: Time from main menu to in-game was 101.78393 seconds > ``` Oh! Awesome! Thanks for investigating. I'll do exactly that as soon as I get to updating.

unilock commented

2026-03-18 14:25:49 +00:00

Author

This is still about 60 seconds more than it would be without Menderman entirely, but it's definitely an improvement.

For the record, ItemStack#isDamageableItem is called in AnvilMenu as well (prior to Item#isValidRepairItem), so it shouldn't cause anything unintended in Menderman.

EDIT: Maybe it would be helpful to log before and after Menderman calculates repair items? I.e. with a timer, like what ModernFix does for world load time.

This is still about 60 seconds more than it would be without Menderman entirely, but it's definitely an improvement. For the record, `ItemStack#isDamageableItem` is called in `AnvilMenu` as well (prior to `Item#isValidRepairItem`), so it shouldn't cause anything unintended in Menderman. EDIT: Maybe it would be helpful to log before and after Menderman calculates repair items? I.e. with a timer, like what ModernFix does for world load time.

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[NeoForge 1.21.1] Server thread hangs when creating new world in large modpack #3