Describe the bug
World downloader is not responding every few minutes and I must restart it. Can I do something with it ?
Screenshots

Version
- Game: Minecraft 1.12.2
- Downloader: latest
Any sort of error message if you open the settings when the red text appears?
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
at org.apache.commons.io.output.AbstractByteArrayOutputStream.needNewBuffer(AbstractByteArrayOutputStream.java:106)
at org.apache.commons.io.output.AbstractByteArrayOutputStream.writeImpl(AbstractByteArrayOutputStream.java:135)
at org.apache.commons.io.output.ByteArrayOutputStream.write(ByteArrayOutputStream.java:66)
at org.apache.commons.io.IOUtils.copyLarge(IOUtils.java:1128)
at org.apache.commons.io.IOUtils.copy(IOUtils.java:849)
at org.apache.commons.io.IOUtils.copyLarge(IOUtils.java:1104)
at org.apache.commons.io.IOUtils.copy(IOUtils.java:825)
at org.apache.commons.io.IOUtils.toByteArray(IOUtils.java:2209)
at game.data.region.McaFile.readFile(McaFile.java:188)
at game.data.region.McaFile.(McaFile.java:40)
at game.data.region.McaFile.(McaFile.java:46)
at game.data.region.McaFile.ofCoords(McaFile.java:97)
at game.data.WorldManager.lambda$loadChunks$4(WorldManager.java:569)
at game.data.WorldManager$$Lambda$1022/0x000000010051b498.apply(Unknown Source)
at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1224)
at game.data.WorldManager.loadChunks(WorldManager.java:569)
at game.data.RenderDistanceExtender.updateFull(RenderDistanceExtender.java:192)
at game.data.RenderDistanceExtender.recompute(RenderDistanceExtender.java:118)
at game.data.RenderDistanceExtender$$Lambda$1021/0x000000010051b278.run(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at java.base/java.lang.Thread.run(Thread.java:831)
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
at org.apache.commons.io.output.AbstractByteArrayOutputStream.needNewBuffer(AbstractByteArrayOutputStream.java:106)
at org.apache.commons.io.output.AbstractByteArrayOutputStream.writeImpl(AbstractByteArrayOutputStream.java:135)
at org.apache.commons.io.output.ByteArrayOutputStream.write(ByteArrayOutputStream.java:66)
at org.apache.commons.io.IOUtils.copyLarge(IOUtils.java:1128)
at org.apache.commons.io.IOUtils.copy(IOUtils.java:849)
at org.apache.commons.io.IOUtils.copyLarge(IOUtils.java:1104)
at org.apache.commons.io.IOUtils.copy(IOUtils.java:825)
at org.apache.commons.io.IOUtils.toByteArray(IOUtils.java:2209)
at game.data.region.McaFile.readFile(McaFile.java:188)
at game.data.region.McaFile.(McaFile.java:65)
at game.data.region.McaFile.(McaFile.java:74)
at game.data.region.Region.(Region.java:45)
at game.data.WorldManager$$Lambda$961/0x000000010050aa98.apply(Unknown Source)
at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1708)
at game.data.WorldManager.loadChunk(WorldManager.java:263)
at game.data.WorldManager.loadChunks(WorldManager.java:602)
at game.data.RenderDistanceExtender.updateFull(RenderDistanceExtender.java:192)
at game.data.RenderDistanceExtender.recompute(RenderDistanceExtender.java:118)
at game.data.RenderDistanceExtender$$Lambda$1021/0x000000010051b278.run(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at java.base/java.lang.Thread.run(Thread.java:831)
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Render Distance Extender" java.lang.OutOfMemoryError: Java heap space
So it seems to be running out of memory. I guess you could try using the "prune overview images" option in the right-click menu, or assigning more heap space to the world downloader process. This will hopefully be fixed eventually (see #149)