Startup profiling

Author: penalosa

.changeset/rich-pots-mate.md

@@ -0,0 +1,7 @@
+---
+"wrangler": minor
+---
+
+Add `--outfile` to `wrangler deploy` for generating a worker bundle.
+
+This is an advanced feature that most users won't need to use. When set, Wrangler will output your built Worker bundle in a Cloudflare specific format that captures all information needed to deploy a Worker using the [Worker Upload API](https://developers.cloudflare.com/api/resources/workers/subresources/scripts/methods/update/)

.changeset/startup-profiling.md

@@ -0,0 +1,12 @@
+---
+"wrangler": minor
+---
+
+Add a `wrangler check startup` command to generate a CPU profile of your Worker's startup phase.
+
+This can be imported into Chrome DevTools or opened directly in VSCode to view a flamegraph of your Worker's startup phase. Additionally, when a Worker deployment fails with a startup time error Wrangler will automatically generate a CPU profile for easy investigation.
+
+Advanced usage:
+
+- `--deploy-args`: to customise the way `wrangler check startup` builds your Worker for analysis, provide the exact arguments you use when deploying your Worker with `wrangler deploy`. For instance, if you deploy your Worker with `wrangler deploy --no-bundle`, you should use `wrangler check startup --deploy-args="--no-bundle"` to profile the startup phase.
+- `--worker-bundle`: if you don't use Wrangler to deploy your Worker, you can use this argument to provide a Worker bundle to analyse. This should be a file path to a serialised multipart upload, with the exact same format as the API expects: https://developers.cloudflare.com/api/resources/workers/subresources/scripts/methods/update/

packages/miniflare/src/index.ts

@@ -767,17 +767,17 @@ export class Miniflare {
 		});
 		// Add custom headers included in response to WebSocket upgrade requests
 		this.#webSocketExtraHeaders = new WeakMap();
-		this.#webSocketServer.on("headers", (headers, req) => {
-			const extra = this.#webSocketExtraHeaders.get(req);
-			this.#webSocketExtraHeaders.delete(req);
-			if (extra) {
-				for (const [key, value] of extra) {
-					if (!restrictedWebSocketUpgradeHeaders.includes(key.toLowerCase())) {
-						headers.push(`${key}: ${value}`);
-					}
-				}
-			}
-		});
+		// this.#webSocketServer.on("headers", (headers, req) => {
+		// 	const extra = this.#webSocketExtraHeaders.get(req);
+		// 	this.#webSocketExtraHeaders.delete(req);
+		// 	if (extra) {
+		// 		for (const [key, value] of extra) {
+		// 			if (!restrictedWebSocketUpgradeHeaders.includes(key.toLowerCase())) {
+		// 				headers.push(`${key}: ${value}`);
+		// 			}
+		// 		}
+		// 	}
+		// });
 
 		// Build path for temporary directory. We don't actually want to create this
 		// unless it's needed (i.e. we have Durable Objects enabled). This means we
@@ -1046,7 +1046,7 @@ export class Miniflare {
 				http.createServer(this.#handleLoopback),
 				/* grace */ 0
 			);
-			server.on("upgrade", this.#handleLoopbackUpgrade);
+			// server.on("upgrade", this.#handleLoopbackUpgrade);
 			server.listen(0, hostname, () => resolve(server));
 		});
 	}