What's new in Chunker 26.2

• More accurate radius handling for pre-generation
• Less extra chunk work around the edge of the selected area
• Better progress tracking so runs stop closer to the requested size
• Safer chunk unloading on Paper and Folia
• Better handling of player-loaded chunks while pre-generation is running
• Faster task tracking behind the scenes
• Updated build version to 26.2

Note: Please report any bugs you find here.

What's new in Chunker 26.1.2

• Updated for Paper/Folia 26.1.2
• Now requires Java 25 (moving forward this will not be backwards compatible with older server versions)
• Updated world and dimension detection for the new Minecraft world folder layout
• Commands now use names like minecraft:overworld, minecraft:the_nether, and minecraft:the_end
• Added optional safety mode for users who want a more careful pregeneration path
• Improved stop/restart handling during pregeneration

Most commands work the same, but world names are now based on the new dimension format.

Example: /pregen 16 5s minecraft:the_nether 2r

Optional safety mode: /pregen 16 5s minecraft:the_nether 2r safety

Note: A lot changed in this version behind the scenes, especially around world detection, Java 25, and the pregeneration safety path. Please report any bugs you find here. You can also check the full release notes here.

What's new in Chunker 1.21.11

• Performance update for pregeneration
• Lower memory use and less lag spikes during heavy runs
• Better handling of chunks around players while pregen is running
• Faster chunk tracking behind the scenes
• Updated for Paper/Folia 1.21.11

This update does not change how you use Chunker. Same commands, same config, just smoother and faster.

Note: Tested on Paper 1.21.11 so far. Please report any issues you encounter here. If you are interested you can check out the more detailed updated release notes

What's new

• You can now choose where pregeneration starts instead of being stuck at one fixed center
• New center setting per world in settings.yml
• If you move the center, Chunker can reset and start pregeneration from the new spot
• Old save files are upgraded automatically to support the new center system
• Spawn chunk radius game rule is no longer touched by the plugin
• Updated for Paper 1.21.10

Example settings.yml setup

Custom centers for two worlds, for example a lobby and a survival world:

# center: Sets where the pregen spiral starts.
# - 'default' uses the world border center, or the world spawn if no border center is set.
# - '~ ~' always uses the current world spawn.
# - 'x z' uses fixed block coordinates, for example: "0 0" or "1500 -500".
lobby:
  auto_run: false
  task_queue_timer: 60
  parallel_tasks_multiplier: auto
  print_update_delay: 5s
  radius: 3000b
  center: 0 0
survival:
  auto_run: false
  task_queue_timer: 60
  parallel_tasks_multiplier: auto
  print_update_delay: 10s
  radius: 15000b
  center: 1500 -500

Note: Tested only on Paper, and Purpur 1.21.10 so far. Please report any issues you encounter here.

If you are interested you can check out the more detailed updated release notes here

What's new

• 10+ additional server optimization options (mob spawning, weather, day/night cycles, etc.)
• Better organization, the settings split into two clean config files
• Full control over what gets optimized or not during pregeneration
• Fixed race conditions that could cause instant completion on first run
• Fixed chunk saving issues on Paper 1.21.0-1.21.2 (old server versions had a bug with chunk saving so some safety was added specifically for those versions for those of you still using them)
• Updated for Folia 1.21.8 compatibility

For Server Owners: Your existing settings will be automatically migrated. Check the new optimizations.yml file to customize which features get disabled during pregeneration for maximum speed.

Note: This is a significant update with lots of changes. Tested on Folia 1.21.8 and Leaf 1.21.8 so far. Please report any issues you encounter.

Changes

• Update to Minecraft 1.21.7.
• A new command /pregen reset <world> lets you restart pregeneration for a world without messing with files.

Bug Fixes

• Fixed an issue where the pre-generation area was too small and didn’t cover what you asked for. User pointed out that when they use 10000b in the command they expect the radius to be 10000b from center outward not edge to edge, so now it is doubled to account for this.
• Fixed extra messages showing up in the console when they weren’t needed. Chunker is smarter about when to show messages. It now only shows "already disabled" messages when a person runs the command, not when the system does it.
• Fixed missing chunks at the edges of the pre-generated area. Chunker now rounds to nearest region if our command falls short to make sure generation is fully covered.

Multi-world / Custom World Support Added

What’s new

Supports any world folder

• If your server runs more than just the default “world”, “world_nether” and “world_the_end”, this release is for you. Now the plugin will detect every world in your server folder, whether it’s a skyblock map, a creative build, or a custom dimension created with Multiverse-Core or other tools.

Auto-update settings.yml

• Upgrading from an older version? No problem. On startup this update will automatically add entries for any missing worlds in your settings.yml, so you can tweak your new worlds just like the originals.

Please let me know if you run into any issues and submit them on the GitHub issue page here.

Chunker – Major Performance & Memory Optimization Update & Support for Folia

This version of Chunker brings significant improvements in memory efficiency, GC behavior, and compatibility — especially under high parallel load configurations.

Improvements

• Coordinate Caching

  • Introduced a lightweight cache for coordinates to reduce frequent object creation and Java GC pressure.
  • This dramatically reduces heap usage during high-throughput pre-generation.

• Memory Leak Fixes

  • Resolved an issue where tracked chunks for players were not being cleared correctly, causing memory to grow over time even after chunks were unloaded. This would only happend if players where in the server and running pregen in the background at the same time.

• Smarter Memory Footprint

  • Optimized several internal variables and data structures to further reduce overall memory usage, especially when running across all 3 dimensions.

• Added Support for Folia

  • Chunker is now fully compatible with Folia servers, alongside all existing supported server types.

Benchmark Results – Memory Usage Comparison

Two tests were performed to compare memory usage between the old and new versions of Chunker, using the same world seed and identical start points.

• Average memory usage reduced by about (50%)
• New version remained stable under extreme chunk rates(about 3200 ChunksPerSecond in the end) that caused the old version to crash.

Benchmark Test Setup (Reproducible)

JVM Launch Parameters (start.bat):

@echo off
java -Xms1G -Xmx30G -XX:+UseG1GC -XX:+UnlockExperimentalVMOptions -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -XX:+OptimizeStringConcat -XX:+UseCompressedOops -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:+ParallelRefProcEnabled -XX:+UseNUMA -XX:ParallelGCThreads=16 -XX:ConcGCThreads=16 -XX:MaxGCPauseMillis=50 -Dusing.aikars.flags=https://mcflags.emc.gs -Daikars.new.flags=true -jar server.jar --nogui
pause

• Xms1G and Xmx30G should be updated to match your minimum(Xms) and max memory(Xmx) you want for your own server
• Update both XX:ParallelGCThreads and XX:ConcGCThreads to match your number of threads

Paper Configuration (paper-global.yml):

chunk-loading-advanced:
  auto-config-send-distance: true
  player-max-concurrent-chunk-generates: -1 # removes per-player generation limits
  player-max-concurrent-chunk-loads: -1     # removes per-player load limits

chunk-loading-basic:
  player-max-chunk-generate-rate: -1.0 # removes chunk generation rate cap
  player-max-chunk-load-rate: -1.0     # removes chunk load rate cap
  player-max-chunk-send-rate: -1.0     # removes chunk send rate cap

chunk-system:
  gen-parallelism: default             # allows Paper to scale based on system threads
  io-threads: 16                       # matches CPU thread count for optimal throughput
  worker-threads: 16                   # matches CPU thread count for chunk processing

region-file-cache-size: 16            # reduced cache size to lower memory usage while pre-generating with no players online; 16 is a balanced middle ground (lowest allowed is 4)

Testing Methodology:

• All world data was reset between tests, except level.dat, to keep the same world seed.
• Chunker plugin data was wiped to start fresh from (0, 0) in each test.
• Each test was run for 1 hour for the parallel_tasks_multiplier 16 test and 15 min for parallel_tasks_multiplier 200 test, allowing memory to stabilize.
• Console print statements may still cause slight memory increases due to terminal buffer growth.

Tips for Best Performance

• Use Paper or Folia with chunk-loading limits removed (as shown above).
• Tune parallel_tasks_multiplier and task_queue_timer based on your system’s CPU core count and available memory.
• Use print_update_delay of 10s+ to avoid excessive log output during long runs.
• Lower region-file-cache-size if running pregen on a fresh world with no players online.