PaperMC/patches/server/0868-Configurable-chat-thread-limit.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Sun, 18 Sep 2022 06:33:17 +0100
Subject: [PATCH] Configurable chat thread limit

By default, spigot shifts chat over to an unbounded thread pool,
on a normal server, this really offers no gains, the creation of a thread
on submitting to the pool on these servers eats more time vs just running it in
the netty pipeline, however, on servers using plugins which do work in here, there
could be some overall benefits to moving this stuff outside of the pipeline.

In general, this patch does two things:
1) Exposes the core size for the pool, this allows for ensuring that a number of threads
sit around in the pool, mitigating the need for creating new threads; This IS however
caveated, the ThreadPoolExecutor will ONLY create core threads as they're needed, it
just won't allow for us to dip back under the # of core threads, this can potentially
be mitigated by calling prestartCoreThread, however, I'm not sure if there is much justification
for this
2) Exposes a max size for the pool, as stated, by default this is unbounded, for most
servers limiting the size of the pool is going to have 0 effects given how fast chat
is actually processed, this is honestly really just exposed for the misnomers or people
who just wanna ensure that this won't grow over a specific size if chat gets stupidly active

diff --git a/src/main/java/io/papermc/paper/configuration/GlobalConfiguration.java b/src/main/java/io/papermc/paper/configuration/GlobalConfiguration.java
index 6a0560b1b0972f90b5260115e81f2baa84cfb40d..4ac3fa45cd155ae8a852e26d4d4d1f16b28efdc2 100644
--- a/src/main/java/io/papermc/paper/configuration/GlobalConfiguration.java
+++ b/src/main/java/io/papermc/paper/configuration/GlobalConfiguration.java
@@ -238,13 +238,26 @@ public class GlobalConfiguration extends ConfigurationPart {
     public Misc misc;
 
     public class Misc extends ConfigurationPart {
+
+        public ChatThreads chatThreads;
         public class ChatThreads extends ConfigurationPart.Post {
             private int chatExecutorCoreSize = -1;
             private int chatExecutorMaxSize = -1;
 
             @Override
             public void postProcess() {
-                // TODO: FILL
+                //noinspection ConstantConditions
+                if (net.minecraft.server.MinecraftServer.getServer() == null) return; // In testing env, this will be null here
+                int _chatExecutorMaxSize = (chatExecutorMaxSize <= 0) ? Integer.MAX_VALUE : chatExecutorMaxSize; // This is somewhat dumb, but, this is the default, do we cap this?;
+                int _chatExecutorCoreSize = Math.max(chatExecutorCoreSize, 0);
+
+                if (_chatExecutorMaxSize < _chatExecutorCoreSize) {
+                    _chatExecutorMaxSize = _chatExecutorCoreSize;
+                }
+
+                java.util.concurrent.ThreadPoolExecutor executor = (java.util.concurrent.ThreadPoolExecutor) net.minecraft.server.MinecraftServer.getServer().chatExecutor;
+                executor.setCorePoolSize(_chatExecutorCoreSize);
+                executor.setMaximumPoolSize(_chatExecutorMaxSize);
             }
         }
         public int maxJoinsPerTick = 5;