Increase maxBuffer for capnp upload (#10217)

veggiedefender · Jesse Li · petebacondarwin · web-flow · commit 979984b8dfd3 · 2025-08-14T10:52:32.000+01:00
* Increase maxBuffer for capnp upload

* extend timeout on multiworker test

---------

Co-authored-by: Jesse Li &lt;jesseli@cloudflare.com&gt;
Co-authored-by: Peter Bacon Darwin &lt;pbacondarwin@cloudflare.com&gt;
diff --git a/.changeset/fifty-tires-kiss.md b/.changeset/fifty-tires-kiss.md
@@ -0,0 +1,5 @@
+---
+"wrangler": patch
+---
+
+Increase the maxBuffer size for capnp uploads
diff --git a/packages/wrangler/e2e/assets-multiworker.test.ts b/packages/wrangler/e2e/assets-multiworker.test.ts
@@ -253,7 +253,8 @@ describe.each(
 					async () =>
 						await expect(
 							fetch(`${url}/hello-from-dee`).then((r) => r.text())
-						).resolves.toBe("hello world from dee")
+						).resolves.toBe("hello world from dee"),
+					{ interval: 1000, timeout: 5_000 }
 				);
 
 				await vi.waitFor(
diff --git a/packages/wrangler/src/deployment-bundle/capnp.ts b/packages/wrangler/src/deployment-bundle/capnp.ts
@@ -20,12 +20,14 @@ export function handleUnsafeCapnp(capnp: CfCapnp): Buffer {
 		);
 	}
 	const srcPrefix = resolve(base_path ?? ".");
-	const capnpProcess = spawnSync("capnp", [
-		"compile",
-		"-o-",
-		`--src-prefix=${srcPrefix}`,
-		...capnpSchemas,
-	]);
+	const capnpProcess = spawnSync(
+		"capnp",
+		["compile", "-o-", `--src-prefix=${srcPrefix}`, ...capnpSchemas],
+		// This number was chosen arbitrarily. If you get ENOBUFS because your compiled schema is still
+		// too large, then we may need to bump this again or figure out another approach.
+		// https://github.com/cloudflare/workers-sdk/pull/10217
+		{ maxBuffer: 3 * 1024 * 1024 }
+	);
 	if (capnpProcess.error) {
 		throw capnpProcess.error;
 	}

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"wrangler": patch
 +---
++
 +Increase the maxBuffer size for capnp uploads