Information

Minecraft version: 1.12.2
Modloader: Forge
Forge version: 14.23.5.2860
Environment: Singleplayer

Mod name: collective
Mod version: 1.12.2-3.0

Description

Causes a leak. Tested on pure minecraft only with this mod. There is a leak constantly, visible in debug.log

debug.log

[11:11:34] [Server thread/DEBUG] [FML]: The world 6d6a3835 (test2) may have leaked: first encounter (5 occurrences).
[11:11:34] [Server thread/DEBUG] [FML]: The world 58ad9fc7 (test2) may have leaked: first encounter (5 occurrences).

[11:12:14] [Server thread/DEBUG] [FML]: Gathering id map for writing to world save test2
[11:12:24] [Server thread/DEBUG] [FML]: The world 6d6a3835 (test2) may have leaked: seen 10 times.

[11:12:24] [Server thread/DEBUG] [FML]: The world 58ad9fc7 (test2) may have leaked: seen 10 times.

[11:12:59] [Server thread/DEBUG] [FML]: Gathering id map for writing to world save test2
[11:13:14] [Server thread/DEBUG] [FML]: The world 6d6a3835 (test2) may have leaked: seen 15 times.

[11:13:14] [Server thread/DEBUG] [FML]: The world 58ad9fc7 (test2) may have leaked: seen 15 times.

[11:13:44] [Server thread/DEBUG] [FML]: Gathering id map for writing to world save test2
[11:14:04] [Server thread/DEBUG] [FML]: The world 6d6a3835 (test2) may have leaked: seen 20 times.

[11:14:04] [Server thread/DEBUG] [FML]: The world 58ad9fc7 (test2) may have leaked: seen 20 times.

[11:14:29] [Server thread/DEBUG] [FML]: Gathering id map for writing to world save test2
[11:14:54] [Server thread/DEBUG] [FML]: The world 6d6a3835 (test2) may have leaked: seen 25 times.
......

Unfortunately there is nothing I can do here. I've dropped support for 1.12 a long time ago, because the code base is now so different. It's the first time I've seen someone having this issue, but won't be able to investigate it. Apologies for the inconvenience.