diff --git a/Spigot-Server-Patches/0505-Stop-copy-on-write-operations-for-updating-light-dat.patch b/Spigot-Server-Patches/0505-Stop-copy-on-write-operations-for-updating-light-dat.patch
new file mode 100644
index 0000000000..33af1075d3
--- /dev/null
+++ b/Spigot-Server-Patches/0505-Stop-copy-on-write-operations-for-updating-light-dat.patch
@@ -0,0 +1,300 @@
+From 4ba6af90544b8cf6d3da553a565e88c397dc8041 Mon Sep 17 00:00:00 2001
+From: Spottedleaf <spottedleaf@spottedleaf.dev>
+Date: Mon, 27 Apr 2020 04:05:38 -0700
+Subject: [PATCH] Stop copy-on-write operations for updating light data
+
+Causes huge memory allocations + gc issues
+
+diff --git a/src/main/java/net/minecraft/server/LightEngineStorage.java b/src/main/java/net/minecraft/server/LightEngineStorage.java
+index a3f919816e..88277d23c3 100644
+--- a/src/main/java/net/minecraft/server/LightEngineStorage.java
++++ b/src/main/java/net/minecraft/server/LightEngineStorage.java
+@@ -19,8 +19,8 @@ public abstract class LightEngineStorage<M extends LightEngineStorageArray<M>> e
+     protected final LongSet b = new LongOpenHashSet();
+     protected final LongSet c = new LongOpenHashSet();
+     protected final LongSet d = new LongOpenHashSet();
+-    protected volatile M e;
+-    protected final M f;
++    protected volatile M e_visible; protected final Object visibleUpdateLock = new Object(); // Paper - diff on change, should be "visible" - force compile fail on usage change
++    protected final M f; // Paper - diff on change, should be "updating"
+     protected final LongSet g = new LongOpenHashSet();
+     protected final LongSet h = new LongOpenHashSet();
+     protected final Long2ObjectMap<NibbleArray> i = Long2ObjectMaps.synchronize(new Long2ObjectOpenHashMap());
+@@ -33,8 +33,8 @@ public abstract class LightEngineStorage<M extends LightEngineStorageArray<M>> e
+         this.l = enumskyblock;
+         this.m = ilightaccess;
+         this.f = m0;
+-        this.e = m0.b();
+-        this.e.d();
++        this.e_visible = m0.b(); // Paper - avoid copying light data
++        this.e_visible.d(); // Paper - avoid copying light data
+     }
+ 
+     protected boolean g(long i) {
+@@ -43,7 +43,15 @@ public abstract class LightEngineStorage<M extends LightEngineStorageArray<M>> e
+ 
+     @Nullable
+     protected NibbleArray a(long i, boolean flag) {
+-        return this.a(flag ? this.f : this.e, i);
++        // Paper start - avoid copying light data
++        if (flag) {
++            return this.a(this.f, i);
++        } else {
++            synchronized (this.visibleUpdateLock) {
++                return this.a(this.e_visible, i);
++            }
++        }
++        // Paper end - avoid copying light data
+     }
+ 
+     @Nullable
+@@ -340,10 +348,12 @@ public abstract class LightEngineStorage<M extends LightEngineStorageArray<M>> e
+ 
+     protected void e() {
+         if (!this.g.isEmpty()) {
++            synchronized (this.visibleUpdateLock) { // Paper - avoid copying light data
+             M m0 = this.f.b();
+ 
+             m0.d();
+-            this.e = m0;
++            this.e_visible = m0; // Paper - avoid copying light data
++            } // Paper - avoid copying light data
+             this.g.clear();
+         }
+ 
+diff --git a/src/main/java/net/minecraft/server/LightEngineStorageArray.java b/src/main/java/net/minecraft/server/LightEngineStorageArray.java
+index b978723a66..278aec8846 100644
+--- a/src/main/java/net/minecraft/server/LightEngineStorageArray.java
++++ b/src/main/java/net/minecraft/server/LightEngineStorageArray.java
+@@ -8,10 +8,17 @@ public abstract class LightEngineStorageArray<M extends LightEngineStorageArray<
+     private final long[] b = new long[2];
+     private final NibbleArray[] c = new NibbleArray[2];
+     private boolean d;
+-    protected final Long2ObjectOpenHashMap<NibbleArray> a;
++    protected final com.destroystokyo.paper.util.map.QueuedChangesMapLong2Object<NibbleArray> data; // Paper - avoid copying light data
++    protected final boolean isVisible; // Paper - avoid copying light data
+ 
+-    protected LightEngineStorageArray(Long2ObjectOpenHashMap<NibbleArray> long2objectopenhashmap) {
+-        this.a = long2objectopenhashmap;
++    // Paper start - avoid copying light data
++    protected LightEngineStorageArray(com.destroystokyo.paper.util.map.QueuedChangesMapLong2Object<NibbleArray> data, boolean isVisible) {
++        if (isVisible) {
++            data.performUpdatesLockMap();
++        }
++        this.data = data;
++        this.isVisible = isVisible;
++        // Paper end - avoid copying light data
+         this.c();
+         this.d = true;
+     }
+@@ -19,12 +26,13 @@ public abstract class LightEngineStorageArray<M extends LightEngineStorageArray<
+     public abstract M b();
+ 
+     public void a(long i) {
+-        this.a.put(i, ((NibbleArray) this.a.get(i)).b());
++        if (this.isVisible) { throw new IllegalStateException("writing to visible data"); } // Paper - avoid copying light data
++        this.data.queueUpdate(i, ((NibbleArray) this.data.getUpdating(i)).b()); // Paper - avoid copying light data
+         this.c();
+     }
+ 
+     public boolean b(long i) {
+-        return this.a.containsKey(i);
++        return this.isVisible ? this.data.visibleContainsKeyAsync(i) : this.data.updatingContainsKey(i); // Paper - avoid copying light data
+     }
+ 
+     @Nullable
+@@ -37,7 +45,7 @@ public abstract class LightEngineStorageArray<M extends LightEngineStorageArray<
+             }
+         }
+ 
+-        NibbleArray nibblearray = (NibbleArray) this.a.get(i);
++        NibbleArray nibblearray = (NibbleArray) (this.isVisible ? this.data.getVisibleAsync(i) : this.data.getUpdating(i)); // Paper - avoid copying light data
+ 
+         if (nibblearray == null) {
+             return null;
+@@ -58,11 +66,13 @@ public abstract class LightEngineStorageArray<M extends LightEngineStorageArray<
+ 
+     @Nullable
+     public NibbleArray d(long i) {
+-        return (NibbleArray) this.a.remove(i);
++        if (this.isVisible) { throw new IllegalStateException("writing to visible data"); } // Paper - avoid copying light data
++        return (NibbleArray) this.data.queueRemove(i); // Paper - avoid copying light data
+     }
+ 
+     public void a(long i, NibbleArray nibblearray) {
+-        this.a.put(i, nibblearray);
++        if (this.isVisible) { throw new IllegalStateException("writing to visible data"); } // Paper - avoid copying light data
++        this.data.queueUpdate(i, nibblearray); // Paper - avoid copying light data
+     }
+ 
+     public void c() {
+diff --git a/src/main/java/net/minecraft/server/LightEngineStorageBlock.java b/src/main/java/net/minecraft/server/LightEngineStorageBlock.java
+index 0f7f4744d9..292d8c742d 100644
+--- a/src/main/java/net/minecraft/server/LightEngineStorageBlock.java
++++ b/src/main/java/net/minecraft/server/LightEngineStorageBlock.java
+@@ -5,7 +5,7 @@ import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
+ public class LightEngineStorageBlock extends LightEngineStorage<LightEngineStorageBlock.a> {
+ 
+     protected LightEngineStorageBlock(ILightAccess ilightaccess) {
+-        super(EnumSkyBlock.BLOCK, ilightaccess, new LightEngineStorageBlock.a(new Long2ObjectOpenHashMap()));
++        super(EnumSkyBlock.BLOCK, ilightaccess, new LightEngineStorageBlock.a(new com.destroystokyo.paper.util.map.QueuedChangesMapLong2Object<>(), false)); // Paper - avoid copying light data
+     }
+ 
+     @Override
+@@ -18,13 +18,13 @@ public class LightEngineStorageBlock extends LightEngineStorage<LightEngineStora
+ 
+     public static final class a extends LightEngineStorageArray<LightEngineStorageBlock.a> {
+ 
+-        public a(Long2ObjectOpenHashMap<NibbleArray> long2objectopenhashmap) {
+-            super(long2objectopenhashmap);
++        public a(com.destroystokyo.paper.util.map.QueuedChangesMapLong2Object<NibbleArray> long2objectopenhashmap, boolean isVisible) { // Paper - avoid copying light data
++            super(long2objectopenhashmap, isVisible); // Paper - avoid copying light data
+         }
+ 
+         @Override
+         public LightEngineStorageBlock.a b() {
+-            return new LightEngineStorageBlock.a(this.a.clone());
++            return new a(this.data, true); // Paper - avoid copying light data
+         }
+     }
+ }
+diff --git a/src/main/java/net/minecraft/server/LightEngineStorageSky.java b/src/main/java/net/minecraft/server/LightEngineStorageSky.java
+index 75d9065b32..06bc8371fe 100644
+--- a/src/main/java/net/minecraft/server/LightEngineStorageSky.java
++++ b/src/main/java/net/minecraft/server/LightEngineStorageSky.java
+@@ -17,15 +17,16 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+     private volatile boolean p;
+ 
+     protected LightEngineStorageSky(ILightAccess ilightaccess) {
+-        super(EnumSkyBlock.SKY, ilightaccess, new LightEngineStorageSky.a(new Long2ObjectOpenHashMap(), new Long2IntOpenHashMap(), Integer.MAX_VALUE));
++        super(EnumSkyBlock.SKY, ilightaccess, new LightEngineStorageSky.a(new com.destroystokyo.paper.util.map.QueuedChangesMapLong2Object<>(), new com.destroystokyo.paper.util.map.QueuedChangesMapLong2Int(), Integer.MAX_VALUE, false)); // Paper - avoid copying light data
+     }
+ 
+     @Override
+     protected int d(long i) {
+         long j = SectionPosition.e(i);
+         int k = SectionPosition.c(j);
+-        LightEngineStorageSky.a lightenginestoragesky_a = (LightEngineStorageSky.a) this.e;
+-        int l = lightenginestoragesky_a.c.get(SectionPosition.f(j));
++        synchronized (this.visibleUpdateLock) { // Paper - avoid copying light data
++        LightEngineStorageSky.a lightenginestoragesky_a = (LightEngineStorageSky.a) this.e_visible; // Paper - avoid copying light data - must be after lock acquire
++        int l = lightenginestoragesky_a.otherData.getVisibleAsync(SectionPosition.f(j)); // Paper - avoid copying light data
+ 
+         if (l != lightenginestoragesky_a.b && k < l) {
+             NibbleArray nibblearray = this.a(lightenginestoragesky_a, j); // Paper - decompile fix
+@@ -46,6 +47,7 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+         } else {
+             return 15;
+         }
++        } // Paper - avoid copying light data
+     }
+ 
+     @Override
+@@ -54,14 +56,14 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+ 
+         if (((LightEngineStorageSky.a) this.f).b > j) {
+             ((LightEngineStorageSky.a) this.f).b = j;
+-            ((LightEngineStorageSky.a) this.f).c.defaultReturnValue(((LightEngineStorageSky.a) this.f).b);
++            ((LightEngineStorageSky.a) this.f).otherData.queueDefaultReturnValue(((LightEngineStorageSky.a) this.f).b); // Paper - avoid copying light data
+         }
+ 
+         long k = SectionPosition.f(i);
+-        int l = ((LightEngineStorageSky.a) this.f).c.get(k);
++        int l = ((LightEngineStorageSky.a) this.f).otherData.getUpdating(k); // Paper - avoid copying light data
+ 
+         if (l < j + 1) {
+-            ((LightEngineStorageSky.a) this.f).c.put(k, j + 1);
++            ((LightEngineStorageSky.a) this.f).otherData.queueUpdate(k, j + 1); // Paper - avoid copying light data
+             if (this.o.contains(k)) {
+                 this.q(i);
+                 if (l > ((LightEngineStorageSky.a) this.f).b) {
+@@ -101,7 +103,7 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+ 
+         int k = SectionPosition.c(i);
+ 
+-        if (((LightEngineStorageSky.a) this.f).c.get(j) == k + 1) {
++        if (((LightEngineStorageSky.a) this.f).otherData.getUpdating(j) == k + 1) { // Paper - avoid copying light data
+             long l;
+ 
+             for (l = i; !this.g(l) && this.a(k); l = SectionPosition.a(l, EnumDirection.DOWN)) {
+@@ -109,12 +111,12 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+             }
+ 
+             if (this.g(l)) {
+-                ((LightEngineStorageSky.a) this.f).c.put(j, k + 1);
++                ((LightEngineStorageSky.a) this.f).otherData.queueUpdate(j, k + 1); // Paper - avoid copying light data
+                 if (flag) {
+                     this.q(l);
+                 }
+             } else {
+-                ((LightEngineStorageSky.a) this.f).c.remove(j);
++                ((LightEngineStorageSky.a) this.f).otherData.queueRemove(j); // Paper - avoid copying light data
+             }
+         }
+ 
+@@ -128,7 +130,7 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+     protected void b(long i, boolean flag) {
+         this.d();
+         if (flag && this.o.add(i)) {
+-            int j = ((LightEngineStorageSky.a) this.f).c.get(i);
++            int j = ((LightEngineStorageSky.a) this.f).otherData.getUpdating(i); // Paper - avoid copying light data
+ 
+             if (j != ((LightEngineStorageSky.a) this.f).b) {
+                 long k = SectionPosition.b(SectionPosition.b(i), j - 1, SectionPosition.d(i));
+@@ -155,7 +157,7 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+             return nibblearray;
+         } else {
+             long j = SectionPosition.a(i, EnumDirection.UP);
+-            int k = ((LightEngineStorageSky.a) this.f).c.get(SectionPosition.f(i));
++            int k = ((LightEngineStorageSky.a) this.f).otherData.getUpdating(SectionPosition.f(i)); // Paper - avoid copying light data
+ 
+             if (k != ((LightEngineStorageSky.a) this.f).b && SectionPosition.c(j) < k) {
+                 NibbleArray nibblearray1;
+@@ -298,7 +300,7 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+             if (!this.o.contains(l)) {
+                 return false;
+             } else {
+-                int i1 = ((LightEngineStorageSky.a) this.f).c.get(l);
++                int i1 = ((LightEngineStorageSky.a) this.f).otherData.getUpdating(l); // Paper - avoid copying light data
+ 
+                 return SectionPosition.c(i1) == j + 16;
+             }
+@@ -307,7 +309,7 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+ 
+     protected boolean n(long i) {
+         long j = SectionPosition.f(i);
+-        int k = ((LightEngineStorageSky.a) this.f).c.get(j);
++        int k = ((LightEngineStorageSky.a) this.f).otherData.getUpdating(j); // Paper - avoid copying light data
+ 
+         return k == ((LightEngineStorageSky.a) this.f).b || SectionPosition.c(i) >= k;
+     }
+@@ -321,18 +323,20 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+     public static final class a extends LightEngineStorageArray<LightEngineStorageSky.a> {
+ 
+         private int b;
+-        private final Long2IntOpenHashMap c;
++        private final com.destroystokyo.paper.util.map.QueuedChangesMapLong2Int otherData; // Paper - avoid copying light data
+ 
+-        public a(Long2ObjectOpenHashMap<NibbleArray> long2objectopenhashmap, Long2IntOpenHashMap long2intopenhashmap, int i) {
+-            super(long2objectopenhashmap);
+-            this.c = long2intopenhashmap;
+-            long2intopenhashmap.defaultReturnValue(i);
++        // Paper start - avoid copying light data
++        public a(com.destroystokyo.paper.util.map.QueuedChangesMapLong2Object<NibbleArray> data, com.destroystokyo.paper.util.map.QueuedChangesMapLong2Int otherData, int i, boolean isVisible) {
++            super(data, isVisible);
++            this.otherData = otherData;
++            // Paper end - avoid copying light data
+             this.b = i;
+         }
+ 
+         @Override
+         public LightEngineStorageSky.a b() {
+-            return new LightEngineStorageSky.a(this.a.clone(), this.c.clone(), this.b);
++            this.otherData.performUpdatesLockMap(); // Paper - avoid copying light data
++            return new LightEngineStorageSky.a(this.data, this.otherData, this.b, true); // Paper - avoid copying light data
+         }
+     }
+ }
+-- 
+2.26.0
+