PaperMC/Unmapped-Spigot-Server-Patches/0195-Disable-Explicit-Network-Manager-Flushing.patch

From 0000000000000000000000000000000000000000 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/network/NetworkManager.java b/src/main/java/net/minecraft/network/NetworkManager.java
index 60e4a4aa3854aaeb250d1318f2f25cf3591ea1d3..297820baef99e97e1216a64c527219e9ccc3e320 100644
--- a/src/main/java/net/minecraft/network/NetworkManager.java
+++ b/src/main/java/net/minecraft/network/NetworkManager.java
@@ -73,6 +73,7 @@ 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) {
@@ -240,7 +241,7 @@ 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.t++ % 20 == 0) {