PaperMC/patches/server/0733-Optimise-non-flush-packet-sending.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: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Tue, 22 Sep 2020 01:49:19 -0700
Subject: [PATCH] Optimise non-flush packet sending
Places like entity tracking make heavy use of packet sending,
and internally netty will use some very expensive thread wakeup
calls when scheduling.
Thanks to various hacks in ProtocolLib as well as other
plugins, we cannot simply use a queue of packets to group
send on execute. We have to call execute for each packet.
Tux's suggestion here is exactly what was needed - tag
the Runnable indicating it should not make a wakeup call.
Big thanks to Tux for making this possible as I had given
up on this optimisation before he came along.
Locally this patch drops the entity tracker tick by a full 1.5x.
diff --git a/src/main/java/net/minecraft/network/Connection.java b/src/main/java/net/minecraft/network/Connection.java
index 335d9e5f11ad3469f3a0310782e41283973f5a5f..957fc22a6c79fd480fefc3cce9cc374d25bc8cf9 100644
--- a/src/main/java/net/minecraft/network/Connection.java
+++ b/src/main/java/net/minecraft/network/Connection.java
@@ -46,6 +46,8 @@ import org.slf4j.Logger;
import org.slf4j.Marker;
import org.slf4j.MarkerFactory;
+
+import io.netty.util.concurrent.AbstractEventExecutor; // Paper
public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
private static final float AVERAGE_PACKETS_SMOOTHING = 0.75F;
@@ -418,9 +420,19 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
if (this.channel.eventLoop().inEventLoop()) {
this.doSendPacket(packet, callbacks, enumprotocol, enumprotocol1, flush); // Paper
} else {
+ // Paper start - optimise packets that are not flushed
+ // note: since the type is not dynamic here, we need to actually copy the old executor code
+ // into two branches. On conflict, just re-copy - no changes were made inside the executor code.
+ if (!flush) {
+ AbstractEventExecutor.LazyRunnable run = () -> {
+ this.doSendPacket(packet, callbacks, enumprotocol, enumprotocol1, flush); // Paper - add flush parameter
+ };
+ this.channel.eventLoop().execute(run);
+ } else { // Paper end - optimise packets that are not flushed
this.channel.eventLoop().execute(() -> {
- this.doSendPacket(packet, callbacks, enumprotocol, enumprotocol1, flush); // Paper
+ this.doSendPacket(packet, callbacks, enumprotocol, enumprotocol1, flush); // Paper - add flush parameter // Paper - diff on change
});
+ } // Paper
}
}