Paper/patches/server/0103-Avoid-blocking-on-Network-Manager-creation.patch
Spottedleaf 01a13871de
Rewrite chunk system (#8177)
Patch documentation to come

Issues with the old system that are fixed now:
- World generation does not scale with cpu cores effectively.
- Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps.
- Unreliable prioritisation of chunk gen/load calls that block the main thread.
- Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved.
- Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal.
- Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles.

The above list is not complete. The patch documentation will complete it.

New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil.

Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft.

The old legacy chunk system patches have been moved to the removed folder in case we need them again.
2022-09-26 01:02:51 -07:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 16 May 2016 23:19:16 -0400
Subject: [PATCH] Avoid blocking on Network Manager creation
Per Paper issue 294
diff --git a/src/main/java/net/minecraft/server/network/ServerConnectionListener.java b/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
index a44520e8fb35d349d6481f369e39db1fdb475749..0e04532b8f1d48116eb46dcef7952bfcc0d11394 100644
--- a/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
+++ b/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
@@ -63,6 +63,15 @@ public class ServerConnectionListener {
public volatile boolean running;
private final List<ChannelFuture> channels = Collections.synchronizedList(Lists.newArrayList());
final List<Connection> connections = Collections.synchronizedList(Lists.newArrayList());
+ // Paper start - prevent blocking on adding a new network manager while the server is ticking
+ private final java.util.Queue<Connection> pending = new java.util.concurrent.ConcurrentLinkedQueue<>();
+ private final void addPending() {
+ Connection manager = null;
+ while ((manager = pending.poll()) != null) {
+ connections.add(manager);
+ }
+ }
+ // Paper end
public ServerConnectionListener(MinecraftServer server) {
this.server = server;
@@ -98,7 +107,8 @@ public class ServerConnectionListener {
int j = ServerConnectionListener.this.server.getRateLimitPacketsPerSecond();
Object object = j > 0 ? new RateKickingConnection(j) : new Connection(PacketFlow.SERVERBOUND);
- ServerConnectionListener.this.connections.add((Connection) object); // CraftBukkit - decompile error
+ // ServerConnectionListener.this.connections.add((Connection) object); // CraftBukkit - decompile error
+ pending.add((Connection) object); // Paper
channel.pipeline().addLast("packet_handler", (ChannelHandler) object);
((Connection) object).setListener(new ServerHandshakePacketListenerImpl(ServerConnectionListener.this.server, (Connection) object));
}
@@ -157,6 +167,7 @@ public class ServerConnectionListener {
synchronized (this.connections) {
// Spigot Start
+ this.addPending(); // Paper
// This prevents players from 'gaming' the server, and strategically relogging to increase their position in the tick order
if ( org.spigotmc.SpigotConfig.playerShuffle > 0 && MinecraftServer.currentTick % org.spigotmc.SpigotConfig.playerShuffle == 0 )
{