From a9a0a672f0e751f3df5c8ae757ad57f9d2b5e155 Mon Sep 17 00:00:00 2001
From: themode <themode@outlook.fr>
Date: Sat, 20 Mar 2021 10:20:45 +0100
Subject: [PATCH] Reduce deflater level, prevent race condition when releasing
 tick buffer

---
 .../minestom/server/network/netty/channel/ClientChannel.java | 5 ++++-
 .../server/network/netty/codec/PacketCompressor.java         | 2 +-
 src/main/java/net/minestom/server/utils/PacketUtils.java     | 2 +-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/main/java/net/minestom/server/network/netty/channel/ClientChannel.java b/src/main/java/net/minestom/server/network/netty/channel/ClientChannel.java
index ad9abe2d9..f915afccf 100644
--- a/src/main/java/net/minestom/server/network/netty/channel/ClientChannel.java
+++ b/src/main/java/net/minestom/server/network/netty/channel/ClientChannel.java
@@ -71,7 +71,10 @@ public class ClientChannel extends SimpleChannelInboundHandler<InboundPacket> {
 
             // Release tick buffer
             if (playerConnection instanceof NettyPlayerConnection) {
-                ((NettyPlayerConnection) playerConnection).getTickBuffer().release();
+                final ByteBuf tickBuffer = ((NettyPlayerConnection) playerConnection).getTickBuffer();
+                synchronized (tickBuffer) {
+                    tickBuffer.release();
+                }
             }
         }
     }
diff --git a/src/main/java/net/minestom/server/network/netty/codec/PacketCompressor.java b/src/main/java/net/minestom/server/network/netty/codec/PacketCompressor.java
index 514f9f90d..ebee11ebc 100644
--- a/src/main/java/net/minestom/server/network/netty/codec/PacketCompressor.java
+++ b/src/main/java/net/minestom/server/network/netty/codec/PacketCompressor.java
@@ -36,7 +36,7 @@ public class PacketCompressor extends ByteToMessageCodec<ByteBuf> {
 
     private final byte[] buffer = new byte[8192];
 
-    private final Deflater deflater = new Deflater();
+    private final Deflater deflater = new Deflater(3);
     private final Inflater inflater = new Inflater();
 
     public PacketCompressor(int threshold) {
diff --git a/src/main/java/net/minestom/server/utils/PacketUtils.java b/src/main/java/net/minestom/server/utils/PacketUtils.java
index b391f96c2..bf71ecb88 100644
--- a/src/main/java/net/minestom/server/utils/PacketUtils.java
+++ b/src/main/java/net/minestom/server/utils/PacketUtils.java
@@ -25,7 +25,7 @@ import java.util.zip.Deflater;
 public final class PacketUtils {
 
     private static final PacketListenerManager PACKET_LISTENER_MANAGER = MinecraftServer.getPacketListenerManager();
-    private static final ThreadLocal<Deflater> DEFLATER = ThreadLocal.withInitial(Deflater::new);
+    private static final ThreadLocal<Deflater> DEFLATER = ThreadLocal.withInitial(() -> new Deflater(3));
 
     private PacketUtils() {