From d42cc4f984656e5ff394ed4c22bfebc5eeaf73eb Mon Sep 17 00:00:00 2001
From: Andrew Steinborn <git@steinborn.me>
Date: Tue, 4 May 2021 18:51:01 -0400
Subject: [PATCH] Force a flush after a certain threshold of packets have been
 queued for sending

Fixes #486.
---
 .../backend/BackendPlaySessionHandler.java          | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java b/proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java
index d649b4c07..b3c7133cf 100644
--- a/proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java
+++ b/proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java
@@ -56,12 +56,16 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
   private static final Logger logger = LogManager.getLogger(BackendPlaySessionHandler.class);
   private static final boolean BACKPRESSURE_LOG = Boolean
       .getBoolean("velocity.log-server-backpressure");
+  private static final int MAXIMUM_PACKETS_TO_FLUSH = Integer
+      .getInteger("velocity.max-packets-per-flush", 8192);
+
   private final VelocityServer server;
   private final VelocityServerConnection serverConn;
   private final ClientPlaySessionHandler playerSessionHandler;
   private final MinecraftConnection playerConnection;
   private final BungeeCordMessageResponder bungeecordMessageResponder;
   private boolean exceptionTriggered = false;
+  private int packetsFlushed;
 
   BackendPlaySessionHandler(VelocityServer server, VelocityServerConnection serverConn) {
     this.server = server;
@@ -271,16 +275,25 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
       ((PluginMessage) packet).retain();
     }
     playerConnection.delayedWrite(packet);
+    if (++packetsFlushed >= MAXIMUM_PACKETS_TO_FLUSH) {
+      playerConnection.flush();
+      packetsFlushed = 0;
+    }
   }
 
   @Override
   public void handleUnknown(ByteBuf buf) {
     playerConnection.delayedWrite(buf.retain());
+    if (++packetsFlushed >= MAXIMUM_PACKETS_TO_FLUSH) {
+      playerConnection.flush();
+      packetsFlushed = 0;
+    }
   }
 
   @Override
   public void readCompleted() {
     playerConnection.flush();
+    packetsFlushed = 0;
   }
 
   @Override