add RenderManager: improve CPU control with global render queue and parallel trace pooling

src/main/java/eu/mhsl/minecraft/pixelpics/Main.java

@@ -7,6 +7,7 @@ import eu.mhsl.minecraft.pixelpics.assets.ResourcePackLoader;
 import eu.mhsl.minecraft.pixelpics.assets.TextureCache;
 import eu.mhsl.minecraft.pixelpics.commands.PixelPicsCommand;
 import eu.mhsl.minecraft.pixelpics.listeners.OnMapInitialize;
+import eu.mhsl.minecraft.pixelpics.render.RenderManager;
 import eu.mhsl.minecraft.pixelpics.render.render.DefaultScreenRenderer;
 import eu.mhsl.minecraft.pixelpics.render.tint.BiomeTintProvider;
 import org.bukkit.Bukkit;
@@ -23,6 +24,7 @@ public final class Main extends JavaPlugin {
 
     private ResourcePack resourcePack;
     private DefaultScreenRenderer screenRenderer;
+    private RenderManager renderManager;
 
     public final NamespacedKey pictureIdFlag = new NamespacedKey(this, "imageid");
 
@@ -37,6 +39,9 @@ public final class Main extends JavaPlugin {
     public void onEnable() {
         instance = this;
 
+        saveDefaultConfig();
+        initRenderManager();
+
         Bukkit.getPluginManager().registerEvents(new OnMapInitialize(), this);
         Objects.requireNonNull(Bukkit.getPluginCommand("pixelPic")).setExecutor(new PixelPicsCommand());
 
@@ -48,6 +53,20 @@ public final class Main extends JavaPlugin {
         initRenderer();
     }
 
+    private void initRenderManager() {
+        int cores = Runtime.getRuntime().availableProcessors();
+        int threads = getConfig().getInt("render.threads", 0);
+        if (threads <= 0) threads = Math.max(1, cores - 2);
+        threads = Math.min(threads, cores);
+        int maxConcurrent = Math.max(1, getConfig().getInt("render.max-concurrent", 2));
+        int queueSize = Math.max(0, getConfig().getInt("render.queue-size", 8));
+        int timeoutSeconds = Math.max(1, getConfig().getInt("render.timeout-seconds", 30));
+
+        this.renderManager = new RenderManager(this, threads, maxConcurrent, queueSize, timeoutSeconds);
+        getLogger().info("Render pool: " + threads + " core(s), max " + maxConcurrent
+            + " concurrent, queue " + queueSize + ", timeout " + timeoutSeconds + "s.");
+    }
+
     private void initRenderer() {
         File resourcePackDir = new File(getDataFolder(), "resourcepack");
         if (!resourcePackDir.exists() && !resourcePackDir.mkdirs()) {
@@ -85,7 +104,8 @@ public final class Main extends JavaPlugin {
         eu.mhsl.minecraft.pixelpics.render.entity.cem.BlockEntityBaker blockEntityBaker =
             new eu.mhsl.minecraft.pixelpics.render.entity.cem.BlockEntityBaker(cemLoader, textures, skinCache, font);
 
-        this.screenRenderer = new DefaultScreenRenderer(registry, tintProvider, textures, entityBaker, blockEntityBaker, getLogger());
+        this.screenRenderer = new DefaultScreenRenderer(registry, tintProvider, textures, entityBaker,
+            blockEntityBaker, getLogger(), renderManager.tracePool());
         // Warm the map palette on the main thread so off-thread dithering never triggers its first init.
         eu.mhsl.minecraft.pixelpics.utils.MapColorPalette.size();
         getLogger().info("PixelPics renderer initialized with resource pack assets.");
@@ -94,6 +114,10 @@ public final class Main extends JavaPlugin {
     @Override
     public void onDisable() {
         eu.mhsl.minecraft.pixelpics.survival.SurvivalRecipes.unregister();
+        if (renderManager != null) {
+            renderManager.shutdown();
+            renderManager = null;
+        }
         if (resourcePack != null) {
             resourcePack.close();
             resourcePack = null;
@@ -105,6 +129,11 @@ public final class Main extends JavaPlugin {
         return this.screenRenderer;
     }
 
+    /** The render queue/limiter; always available after {@code onEnable}. */
+    public RenderManager getRenderManager() {
+        return this.renderManager;
+    }
+
     public static Main getInstance() {
         return instance;
     }