Create multiple workers based on number of cores

deno_server.ts

@@ -6,33 +6,56 @@ const States = Object.freeze({
   TIMEOUT: "TIMEOUT",
 });
 
+// Create a pool of workers.
+const workerPool: { worker: Worker; inUse: boolean }[] = [];
+const numWorkers = navigator.hardwareConcurrency;
+
+for (let i = 0; i < numWorkers; i++) {
+  const worker = new Worker(new URL("./worker.ts", import.meta.url).href, {
+    type: "module",
+    deno: {
+      namespace: true,
+      permissions: "inherit",
+    },
+  });
+  workerPool.push({ worker, inUse: false });
+}
+
+function getAvailableWorker() {
+  return new Promise((resolve) => {
+    const check = () => {
+      const availableWorker = workerPool.find((w) => !w.inUse);
+      if (availableWorker) {
+        availableWorker.inUse = true;
+        resolve(availableWorker);
+      } else {
+        setTimeout(check, 100); // Check again in 100ms.
+      }
+    };
+    check();
+  });
+}
+
 async function handler(req: Request): Promise<Response> {
   if (req.method !== "POST" || new URL(req.url).pathname !== "/execute") {
     return new Response("Not Found", { status: 404 });
   }
 
+  const availableWorker = (await getAvailableWorker()) as {
+    worker: Worker;
+    inUse: boolean;
+  };
+
   try {
     const body = await req.json();
     const { code = "", request = {}, environment = {}, name } = body;
 
-    const worker = new Worker(new URL("./worker.ts", import.meta.url).href, {
-      type: "module",
-      // The `deno` option is now stable, but your editor might show a TS error
-      // if it's not configured for Deno. This will run correctly with Deno.
-      deno: {
-        namespace: true, // recommended for workers
-        permissions: "inherit",
-      },
-    });
-
     const executionPromise = new Promise((resolve, reject) => {
-      worker.onmessage = (e) => {
+      availableWorker.worker.onmessage = (e) => {
         resolve(e.data);
-        worker.terminate();
       };
-      worker.onerror = (e) => {
+      availableWorker.worker.onerror = (e) => {
         reject(new Error(`Worker error: ${e.message}`));
-        worker.terminate();
       };
     });
 
@@ -40,7 +63,7 @@ async function handler(req: Request): Promise<Response> {
       setTimeout(() => reject(new Error("Timeout")), TIMEOUT_MS)
     );
 
-    worker.postMessage({ code, request, environment, name });
+    availableWorker.worker.postMessage({ code, request, environment, name });
 
     const startTime = performance.now();
     try {
@@ -49,7 +72,6 @@ async function handler(req: Request): Promise<Response> {
         headers: { "Content-Type": "application/json" },
       });
     } catch (err) {
-      worker.terminate();
       const executionTime = performance.now() - startTime;
       const payload = {
         status: States.TIMEOUT,
@@ -65,9 +87,11 @@ async function handler(req: Request): Promise<Response> {
     }
   } catch (e) {
     return new Response(`Bad Request: ${e.message}`, { status: 400 });
+  } finally {
+    availableWorker.inUse = false; // Release the worker.
   }
 }
 
-console.log("⚡ Deno server ready on :8000");
+console.log(`⚡ Deno server ready on :8000 with ${numWorkers} workers.`);
 
 await serve(handler, { port: 8000 });