papermc/Spigot-Server-Patches/0246-Disable-Explicit-Network-Manager-Flushing.patch

From 2c3e67315b5181b36cb57ac67ebdd9597143ef48 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 11 Mar 2018 14:13:33 -0400
Subject: [PATCH] Disable Explicit Network Manager Flushing

This seems completely pointless, as packet dispatch uses .writeAndFlush.

Things seem to work fine without explicit flushing, but incase issues arise,
provide a System property to re-enable it using improved logic of doing the
flushing on the netty event loop, so it won't do the flush on the main thread.

Renable flushing by passing -Dpaper.explicit-flush=true

diff --git a/src/main/java/net/minecraft/server/NetworkManager.java b/src/main/java/net/minecraft/server/NetworkManager.java
index 424464d09..909ad36fb 100644
--- a/src/main/java/net/minecraft/server/NetworkManager.java
+++ b/src/main/java/net/minecraft/server/NetworkManager.java
@@ -66,6 +66,7 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
     // Paper start - NetworkClient implementation
     public int protocolVersion;
     public java.net.InetSocketAddress virtualHost;
+    private static boolean enableExplicitFlush = Boolean.getBoolean("paper.explicit-flush");
     // Paper end
 
     public NetworkManager(EnumProtocolDirection enumprotocoldirection) {
@@ -236,7 +237,7 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
         }
 
         if (this.channel != null) {
-            this.channel.flush();
+            if (enableExplicitFlush) this.channel.eventLoop().execute(() -> this.channel.flush()); // Paper - we don't need to explicit flush here, but allow opt in incase issues are found to a better version
         }
 
         if (this.u++ % 20 == 0) {
-- 
2.18.0