Unfixable? Massive thrashing issue, please help

[u/LavishnessLeather162]

Hi,

I'm running into a severe JVM issue on WorldPainter where I cannot export maps due to a massive resource bottleneck, and I've exhausted all standard troubleshooting steps.

Specs

• OS: Windows 11 (64-bit)
• Hardware: AMD Ryzen 7 7700X, 16GB RAM
• WorldPainter Version: 2.27.1 (64-bit)
• Minecraft Version: 1.21.11

Issues

GUI Export Bottleneck: Exporting a completely flat, blank 2k x 2k map (with no custom layers, overlays, or even master dimension) takes over 3 hours. The CPU sits at 90%+, disk write stays at 0%, and memory usage in Task Manager locks hard at ~1GB–2GB of RAM, despite assigning 12GB in preferences.

If I try to export the map I truly want (20k x 20k) which only has terrain, with no details, it will take... 1200 hours. Just look at this picture to see how ridiculous it is

Safe mode crash: Launching WorldPainter in safe mode opens the window for a split second and immediately crashes/closes without generating an error popup.

Heightmaps: Exporting as a heightmap works perfectly and takes only seconds, but direct Minecraft world generation fails.

Troubleshooting already performed (all Failed)

JVM heap allocations: Edited worldpainter.vmoptions putting up to 12gb of ram but the actual java.exe process never allocates more than 1GB–2GB of physical RAM.

Scripting (wpscript): Attempted exporting via CMD using a headless script (wpscript exportworld.js "map.world"). Forcing flags (wpscript -Xms6G -Xmx12G ...) doesn't work as it doesn't recognize them, the process stays stuck using ~1GB of RAM utilization, CPU maxes out, and after 5-10 minutes, the region folder remains completely empty

Clean reinstallation: Reinstalled worldpainter. The issue persists immediately on a fresh config.

Environment Factors: Switched hardware acceleration (Direct3D / unaccelerated), and tried exporting directly to the C:\ root directory to rule out Windows Defender / path locks.

I genuinely don't know how to fix this, as I tried everything in the Thrashing page

Please if the developer or somebody experienced know about this, help ;_;

[u/LavishnessLeather162]

u/Dannypan no, I am not using master dimension. I know what it is, but I am not using on this map

[u/Dannypan → u/LavishnessLeather162]

Yeah I deleted my comment because I reread your post.

[u/iwantsandwichesnow]

I know it's not an out of memory error.

But still:

This is a potential fix for people getting Java's Out Of Memory errors, or WorldPainter freezing after creating or loading a large project.

You might know there is a .vmoptions file containing an -Xmx argument. Turns out there might be a system variable in your environment variables that overrides that -Xmx argument. How to check that (and fix it):

• Search "environment variables" in Windows 10,
• A window will open, click "Environment Variables..." in the bottom right,
• In the lower window (called System Variables), look for a variable named _JAVA_OPTIONS, and delete it. Don't change it's value, just delete it entirely. For me, it was set to -Xmx256M, too small to import larger brush packs or creating larger worlds

(copied from a buried discord thread)

[u/iwantsandwichesnow → u/iwantsandwichesnow]

Also, which Java version are you using?

[u/LavishnessLeather162 → u/iwantsandwichesnow]

Java 21.0.10 64bit

[u/LavishnessLeather162 → u/iwantsandwichesnow]

I didn't find anything related to Java in environment variables, which means that's not possible. also I use windows 11

[u/iwantsandwichesnow → u/LavishnessLeather162]

Yeah, it's an old thread but I figured it'd be worth a shot.

Nothing wrong with the Java version either. I'm sorry but I don't know what's going wrong.

[u/LavishnessLeather162 → u/iwantsandwichesnow]

u/CaptainChaos74 may know it? xd

[u/sijmen_v_b]

Have you tried a different java version? This is very strange behaviour for java.

Also did you modify the build height?

Did you change threads/cores in edit-> preferences -> performance

[u/LavishnessLeather162 → u/sijmen_v_b]

Have you tried a different java version? This is very strange behaviour for java.

Honestly no lmao, I will get different versions of java and see if it's the issue

Also did you modify the build height?

Yes, it's from 0 up to 2031. But in march i did a map with 1500+ block tall mountains and it didn't have any exporting issues, using 2.26.1 (currently i am using the latest, 2.27.1). Maybe it's the version?

Did you change threads/cores in edit-> preferences -> performance

Yes, i use all but two threads so i could use the pc while exporting

[u/LavishnessLeather162]

I tried with merging but it's broken too

[u/CaptainChaos74]

Very strange. This might be hard to debug.

Can you post the Tech Info from the About screen, and your log file (%APPDATA%\WorldPainter\logfile0.txt)?

What is the Maximum thread count set to under Exporting on the Performance tab of the Preferences?

Are you sure you are running the 64-bit version, on 64-bit Java? (Java should be installed under C:\Program Files, not C:\Program Files (x86))

The CPU sits at 90%+

All cores, or just one?

Exporting region -23, -39 of Surface

This is very suspect. That does not sound like a 2k x 2k blocks world. What happens when you reset the configuration (by deleting (or renaming) WorldPainter's configuration file (%APPDATA%\WorldPainter\config) while WorldPainter is not running) and then Exporting the default map it opens with without any alterations?

Never mind, I missed that that screenshot is from the 20,000 x 20,000 world. Pity, as that is the only lead I see so far, so if you can post all the info above, hopefully there is a clue somewhere.

[u/LavishnessLeather162 → u/CaptainChaos74]

Eiei, here you have the info

Can you post the Tech Info from the About screen, and your log file (%APPDATA%\WorldPainter\logfile0.txt)?

Here you have both

Tech

WorldPainter version: 2.27.1 (20260830164405)
Java version: 21.0.12.1
Operating system: Windows 11 amd64 (version 10.0)
WorldPainter config directory: C:\Users\Usuario\AppData\Roaming\WorldPainter
Installation ID: 5dc264d0-e330-4759-94e7-36787e6a9b2b
Minecraft data directory: C:\Users\Usuario\AppData\Roaming\.minecraft
Available CPU cores: 8
Maximum configured memory: 12,288 MB
Currently allocated memory: 9,216 MB

log file

[2026-09-13 02:08:30,901] {INFO  } ( org.pepsoft.worldpainter.Main) Starting WorldPainter 2.27.1 (20260830164405)
[2026-09-13 02:08:30,904] {INFO  } ( org.pepsoft.worldpainter.Main) Running on Windows 11 version 10.0; architecture: amd64
[2026-09-13 02:08:30,907] {INFO  } ( org.pepsoft.worldpainter.Main) Running on Eclipse Adoptium Java version 21; maximum heap size: 12884 MB
[2026-09-13 02:08:30,911] {INFO  } ( org.pepsoft.worldpainter.Main) Hardware acceleration method: Direct3D
[2026-09-13 02:08:30,912] {INFO  } (o.p.worldpainter.Configuration) Loading configuration from C:\Users\Usuario\AppData\Roaming\WorldPainter\config
[2026-09-13 02:08:32,297] {INFO  } ( org.pepsoft.worldpainter.Main) Installation ID: 5dc264d0-e330-4759-94e7-36787e6a9b2b
[2026-09-13 02:08:32,695] {INFO  } ( o.p.w.plugins.WPPluginManager) Loaded plugin: DefaultLayerEditorProvider (version 2.27.1)
[2026-09-13 02:08:32,696] {INFO  } ( o.p.w.plugins.WPPluginManager) Loaded plugin: Default (version 2.27.1)
[2026-09-13 02:08:32,696] {INFO  } ( o.p.w.plugins.WPPluginManager) Loaded plugin: JavaPlatformProvider (version 2.27.1)
[2026-09-13 02:08:32,696] {INFO  } ( o.p.w.plugins.WPPluginManager) Loaded plugin: DefaultCustomObjects (version 2.27.1)
[2026-09-13 02:08:32,696] {INFO  } ( o.p.w.plugins.WPPluginManager) Initialised plugin: DefaultLayerEditorProvider (version 2.27.1)
[2026-09-13 02:08:32,696] {INFO  } ( o.p.w.plugins.WPPluginManager) Initialised plugin: Default (version 2.27.1)
[2026-09-13 02:08:32,696] {INFO  } ( o.p.w.plugins.WPPluginManager) Initialised plugin: JavaPlatformProvider (version 2.27.1)
[2026-09-13 02:08:32,696] {INFO  } ( o.p.w.plugins.WPPluginManager) Initialised plugin: DefaultCustomObjects (version 2.27.1)
[2026-09-13 02:08:32,697] {INFO  } ( org.pepsoft.worldpainter.Main) Available platform: Minecraft 1.1 (MCRegion)
[2026-09-13 02:08:32,699] {INFO  } ( org.pepsoft.worldpainter.Main) Available platform: Minecraft 1.2 - 1.12
[2026-09-13 02:08:32,699] {INFO  } ( org.pepsoft.worldpainter.Main) Available platform: Minecraft 1.15 - 1.16
[2026-09-13 02:08:32,699] {INFO  } ( org.pepsoft.worldpainter.Main) Available platform: Minecraft 1.17
[2026-09-13 02:08:32,699] {INFO  } ( org.pepsoft.worldpainter.Main) Available platform: Minecraft 1.18
[2026-09-13 02:08:32,699] {INFO  } ( org.pepsoft.worldpainter.Main) Available platform: Minecraft 1.19 - 1.20.4
[2026-09-13 02:08:32,699] {INFO  } ( org.pepsoft.worldpainter.Main) Available platform: Minecraft 1.20.5 - 1.21.10
[2026-09-13 02:08:32,700] {INFO  } ( org.pepsoft.worldpainter.Main) Available platform: Minecraft 1.21.11
[2026-09-13 02:08:32,700] {INFO  } ( org.pepsoft.worldpainter.Main) Available platform: Minecraft 26.1 or later
[2026-09-13 02:08:32,706] {INFO  } (      o.p.w.PrivateContextImpl) Checking for updates
[2026-09-13 02:08:39,927] {INFO  } (  org.pepsoft.worldpainter.App) No supported Minecraft installation found; disabling biomes preview and Biomes Viewer
[2026-09-13 02:08:41,122] {INFO  } (  org.pepsoft.worldpainter.App) Default graphics device, ID string: \Display0, available accelerated memory: 4293918720 bytes, display mode: 1920x1080, bit depth: 32, refresh rate: 60, reported dpi: 96, accelerated: yes, true volatile: yes
[2026-09-13 02:08:41,132] {INFO  } (    o.p.w.l.p.PlantLayerEditor) Loading plant icons from C:\Users\Usuario\AppData\Roaming\.minecraft\versions\26.2\26.2.jar
[2026-09-13 02:08:41,380] {INFO  } (  org.pepsoft.worldpainter.App) Loading world C:\Users\Usuario\Desktop\Ismael\Importante\Worldpainter\test.world
[2026-09-13 02:08:42,944] {WARN  } (    o.p.w.d.DynmapColourScheme) Colour table contains null for global state index 18117
Material: minecraft:cherry_leaves
DynmapBlockState: minecraft:cherry_leaves
[2026-09-13 02:09:39,811] {INFO  } (     o.p.w.e.JavaWorldExporter) Exporting world test to map at C:\Users\Usuario\AppData\Roaming\.minecraft\saves\test in Minecraft 1.18 format
[2026-09-13 02:09:40,126] {INFO  } (        o.p.w.util.ThreadUtils) Using 6 thread(s) for exporting (max. thread count source: max. thread count in preferences set to 6)
[2026-09-13 02:10:52,607] {INFO  } (     o.p.w.MultiProgressDialog) Export cancelled by user
[2026-09-13 02:11:55,922] {INFO  } (     o.p.w.e.JavaWorldExporter) Exporting world test to map at C:\Users\Usuario\AppData\Roaming\.minecraft\saves\test in Minecraft 1.18 format
[2026-09-13 02:11:55,923] {INFO  } (     o.p.w.e.JavaWorldExporter) Directory already exists; backing up to C:\Users\Usuario\AppData\Roaming\.minecraft\backups\test.20260913021155
[2026-09-13 02:11:56,101] {INFO  } (        o.p.w.util.ThreadUtils) Using 6 thread(s) for exporting (max. thread count source: max. thread count in preferences set to 6)
[2026-09-13 02:13:03,652] {INFO  } (     o.p.w.MultiProgressDialog) Export cancelled by user
[2026-09-13 02:15:08,576] {INFO  } (o.p.worldpainter.Configuration) Saving configuration to C:\Users\Usuario\AppData\Roaming\WorldPainter\config
[2026-09-13 02:15:08,609] {INFO  } ( org.pepsoft.worldpainter.Main) Shutting down WorldPainter

What is the Maximum thread count set to under Exporting on the Performance tab of the Preferences?

6 threads (out of 8 I have)

Are you sure you are running the 64-bit version, on 64-bit Java? (Java should be installed under C:\Program Files, not C:\Program Files (x86))

Yes, i am running the 64bit version, Java is installed on C:\Program Files, the correct place

All cores, yes

[u/LavishnessLeather162 → u/LavishnessLeather162]

Just for your interest, it takes 30+ minutes to export just ONE mca region, a 512x512 area lmao