Adjust thread priorities

src/main/java/org/embeddedt/modernfix/core/config/ModernFixConfig.java

@@ -22,16 +22,20 @@ public class ModernFixConfig {
 
     public static ForgeConfigSpec.ConfigValue<List<? extends String>> BLACKLIST_ASYNC_JEI_PLUGINS;
 
+    public static ForgeConfigSpec.IntValue INTEGRATED_SERVER_PRIORITY;
+    public static ForgeConfigSpec.IntValue BACKGROUND_WORKER_PRIORITY;
+
     public static Set<ResourceLocation> jeiPluginBlacklist;
 
     static {
-        List<? extends String> empty = Collections.emptyList();
         Predicate<Object> locationValidator = o -> o instanceof String && ((String)o).contains(":");
         BLACKLIST_ASYNC_JEI_PLUGINS = COMMON_BUILDER
                 .comment("These JEI plugins will be loaded on the main thread")
                 .defineList("blacklist_async_jei_plugins", ImmutableList.of(
                         "jepb:jei_plugin"
                 ), locationValidator);
+        INTEGRATED_SERVER_PRIORITY = COMMON_BUILDER.comment("Thread priority to use for the integrated server. By default this is one less than the client thread, to help prevent the server from lowering FPS.").defineInRange("integratedServerPriority", 4, 1, 10);
+        BACKGROUND_WORKER_PRIORITY = COMMON_BUILDER.comment("Priority to use for the background workers that complete various tasks. By default this is one less than the client thread.").defineInRange("backgroundWorkerPriority", 4, 1, 10);
     }
 
     static {

src/main/java/org/embeddedt/modernfix/core/config/ModernFixEarlyConfig.java

@@ -1,5 +1,6 @@
 package org.embeddedt.modernfix.core.config;
 
+import net.minecraftforge.fml.loading.FMLLoader;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -27,6 +28,12 @@ public class ModernFixEarlyConfig {
         this.addMixinRule("bugfix.concurrency", true);
         this.addMixinRule("bugfix.edge_chunk_not_saved", true);
         this.addMixinRule("perf.async_jei", true);
+        this.addMixinRule("perf.thread_priorities", true);
+
+        /* Mod compat */
+        if(FMLLoader.getLoadingModList().getModFileById("smoothboot") != null) {
+            this.options.get("mixin.perf.thread_priorities").addModOverride(false, "smoothboot");
+        }
     }
 
     /**

src/main/java/org/embeddedt/modernfix/mixin/perf/thread_priorities/IntegratedServerMixin.java

@@ -0,0 +1,29 @@
+package org.embeddedt.modernfix.mixin.perf.thread_priorities;
+
+import com.mojang.authlib.GameProfileRepository;
+import com.mojang.authlib.minecraft.MinecraftSessionService;
+import net.minecraft.client.Minecraft;
+import net.minecraft.resources.DataPackRegistries;
+import net.minecraft.resources.ResourcePackList;
+import net.minecraft.server.integrated.IntegratedServer;
+import net.minecraft.server.management.PlayerProfileCache;
+import net.minecraft.util.registry.DynamicRegistries;
+import net.minecraft.world.chunk.listener.IChunkStatusListenerFactory;
+import net.minecraft.world.storage.IServerConfiguration;
+import net.minecraft.world.storage.SaveFormat;
+import org.embeddedt.modernfix.ModernFix;
+import org.embeddedt.modernfix.core.config.ModernFixConfig;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(IntegratedServer.class)
+public class IntegratedServerMixin {
+    @Inject(method = "<init>", at = @At("RETURN"))
+    private void adjustServerPriority(Thread pServerThread, Minecraft pMinecraft, DynamicRegistries.Impl pRegistryHolder, SaveFormat.LevelSave pStorageSource, ResourcePackList pPackRepository, DataPackRegistries pResources, IServerConfiguration pWorldData, MinecraftSessionService pSessionService, GameProfileRepository pProfileRepository, PlayerProfileCache pProfileCache, IChunkStatusListenerFactory pProgressListenerfactory, CallbackInfo ci) {
+        int pri = ModernFixConfig.INTEGRATED_SERVER_PRIORITY.get();
+        ModernFix.LOGGER.info("Changing server thread priority to " + pri);
+        pServerThread.setPriority(pri);
+    }
+}

src/main/java/org/embeddedt/modernfix/mixin/perf/thread_priorities/UtilMixin.java

@@ -0,0 +1,25 @@
+package org.embeddedt.modernfix.mixin.perf.thread_priorities;
+
+import net.minecraft.util.Util;
+import org.embeddedt.modernfix.ModernFix;
+import org.embeddedt.modernfix.core.config.ModernFixConfig;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyArg;
+
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.ForkJoinWorkerThread;
+
+@Mixin(Util.class)
+public class UtilMixin {
+    @ModifyArg(method = "makeExecutor", at = @At(value = "INVOKE", target = "Ljava/util/concurrent/ForkJoinPool;<init>(ILjava/util/concurrent/ForkJoinPool$ForkJoinWorkerThreadFactory;Ljava/lang/Thread$UncaughtExceptionHandler;Z)V"), index = 1)
+    private static ForkJoinPool.ForkJoinWorkerThreadFactory adjustPriorityOfThreadFactory(ForkJoinPool.ForkJoinWorkerThreadFactory factory) {
+        return pool -> {
+            ForkJoinWorkerThread thread = factory.newThread(pool);
+            int pri = ModernFixConfig.BACKGROUND_WORKER_PRIORITY.get();
+            ModernFix.LOGGER.info("Changing priority of " + thread.getName() + " to " + pri);
+            thread.setPriority(pri);
+            return thread;
+        };
+    }
+}

src/main/resources/modernfix.mixins.json

@@ -16,7 +16,8 @@
     "perf.reduce_blockstate_cache_rebuilds.AbstractBlockStateMixin",
     "perf.reduce_blockstate_cache_rebuilds.GameDataMixin",
     "perf.reduce_blockstate_cache_rebuilds.BlockCallbacksMixin",
-    "perf.boost_worker_count.UtilMixin"
+    "perf.boost_worker_count.UtilMixin",
+    "perf.thread_priorities.UtilMixin"
   ],
   "client": [
     "perf.skip_first_datapack_reload.MinecraftMixin",
@@ -29,7 +30,8 @@
     "perf.async_jei.ClientLifecycleHandlerMixin",
     "perf.async_jei.JeiStarterMixin",
     "perf.async_jei.PluginCallerMixin",
-    "perf.async_jei.RecipeManagerInternalMixin"
+    "perf.async_jei.RecipeManagerInternalMixin",
+    "perf.thread_priorities.IntegratedServerMixin"
   ],
   "injectors": {
     "defaultRequire": 1