Increase Light Queue Size

Wiz mentioned that large WorldEdit operations cause light to run on
main thread. The queue was small, set to 5.. this bumps it to 20
but makes it configurable per-world.

The main risk of increasing this higher is during shutdown, some
queued light updates may be lost because mojang did not flush the
light engine on shutdown...

The queue size only puts a cap on max loss, doesn't solve that problem.

Don't touch this unless you know you have a problem and ok with the risk.

Spigot-Server-Patches/0461-Increase-Light-Queue-Size.patch

@@ -0,0 +1,45 @@
+From e1153f57b2ad89bb3036887742013b493efb2117 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Wed, 8 Apr 2020 21:24:05 -0400
+Subject: [PATCH] Increase Light Queue Size
+
+Wiz mentioned that large WorldEdit operations cause light to run on
+main thread. The queue was small, set to 5.. this bumps it to 20
+but makes it configurable per-world.
+
+The main risk of increasing this higher is during shutdown, some
+queued light updates may be lost because mojang did not flush the
+light engine on shutdown...
+
+The queue size only puts a cap on max loss, doesn't solve that problem.
+
+diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+index 659a011e97..88a45e517c 100644
+--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
++++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+@@ -684,4 +684,9 @@ public class PaperWorldConfig {
+     private void trackerUpdateDistance() {
+         trackerUpdateDistance = getDouble("tracker-update-distance", trackerUpdateDistance);
+     }
++
++    public int lightQueueSize = 20;
++    private void lightQueueSize() {
++        lightQueueSize = getInt("light-queue-size", lightQueueSize);
++    }
+ }
+diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
+index c9deaffc4a..06c395000f 100644
+--- a/src/main/java/net/minecraft/server/MinecraftServer.java
++++ b/src/main/java/net/minecraft/server/MinecraftServer.java
+@@ -649,7 +649,7 @@ public abstract class MinecraftServer extends IAsyncTaskHandlerReentrant<TickTas
+         this.executeModerately();
+         // CraftBukkit end
+         worldloadlistener.b();
+-        chunkproviderserver.getLightEngine().a(5);
++        chunkproviderserver.getLightEngine().a(worldserver.paperConfig.lightQueueSize); // Paper - increase light queue size
+ 
+         // CraftBukkit start
+         this.forceTicks = false;
+-- 
+2.25.1
+