1 files changed, 46 insertions, 0 deletions
diff --git a/patches/server/0709-Optimise-non-flush-packet-sending.patch b/patches/server/0709-Optimise-non-flush-packet-sending.patch
new file mode 100644
index 0000000000..fdc4b312bf
--- /dev/null
+++ b/patches/server/0709-Optimise-non-flush-packet-sending.patch
@@ -0,0 +1,46 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Spottedleaf <[email protected]>
+Date: Tue, 22 Sep 2020 01:49:19 -0700
+Subject: [PATCH] Optimise non-flush packet sending
+
+Places like entity tracking make heavy use of packet sending,
+and internally netty will use some very expensive thread wakeup
+calls when scheduling.
+
+Thanks to various hacks in ProtocolLib as well as other
+plugins, we cannot simply use a queue of packets to group
+send on execute. We have to call execute for each packet.
+
+Tux's suggestion here is exactly what was needed - tag
+the Runnable indicating it should not make a wakeup call.
+
+Big thanks to Tux for making this possible as I had given
+up on this optimisation before he came along.
+
+Locally this patch drops the entity tracker tick by a full 1.5x.
+
+diff --git a/src/main/java/net/minecraft/network/Connection.java b/src/main/java/net/minecraft/network/Connection.java
+index 1690626b8a62e078ce23e725c0384983af9c9e23..bff8267b72f5e4a0530055ee58add657fa553dcd 100644
+--- a/src/main/java/net/minecraft/network/Connection.java
++++ b/src/main/java/net/minecraft/network/Connection.java
+@@ -428,9 +428,19 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
+         if (this.channel.eventLoop().inEventLoop()) {
+             this.doSendPacket(packet, callbacks, enumprotocol, enumprotocol1, flush); // Paper
+         } else {
++            // Paper start - optimise packets that are not flushed
++            // note: since the type is not dynamic here, we need to actually copy the old executor code
++            // into two branches. On conflict, just re-copy - no changes were made inside the executor code.
++            if (!flush) {
++                io.netty.util.concurrent.AbstractEventExecutor.LazyRunnable run = () -> {
++                    this.doSendPacket(packet, callbacks, enumprotocol, enumprotocol1, flush); // Paper - add flush parameter
++                };
++                this.channel.eventLoop().execute(run);
++            } else { // Paper end - optimise packets that are not flushed
+             this.channel.eventLoop().execute(() -> {
+-                this.doSendPacket(packet, callbacks, enumprotocol, enumprotocol1, flush); // Paper
++                this.doSendPacket(packet, callbacks, enumprotocol, enumprotocol1, flush); // Paper - add flush parameter // Paper - diff on change
+             });
++            } // Paper
+         }
+ 
+     }