From 666a13a3ae4da0e1c8fbbe15623184f52341bccb Mon Sep 17 00:00:00 2001
From: Gal Schlezinger <gal@spitfire.co.il>
Date: Mon, 28 Feb 2022 11:10:36 +0200
Subject: [PATCH] Load WASM in parallel without blocking the main thread

---
 packages/next/server/web/sandbox/context.ts | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/packages/next/server/web/sandbox/context.ts b/packages/next/server/web/sandbox/context.ts
index 2c56aa841a60..eae4020201e1 100644
--- a/packages/next/server/web/sandbox/context.ts
+++ b/packages/next/server/web/sandbox/context.ts
@@ -1,6 +1,6 @@
 import type { Context } from 'vm'
 import { Blob, File, FormData } from 'next/dist/compiled/formdata-node'
-import { readFileSync } from 'fs'
+import { readFileSync, promises as fs } from 'fs'
 import { requireDependencies } from './require'
 import { TransformStream } from 'next/dist/compiled/web-streams-polyfill'
 import cookie from 'next/dist/compiled/cookie'
@@ -270,9 +270,15 @@ async function loadWasmBindings(
   wasmBindings: WasmBinding[]
 ): Promise<Record<string, WebAssembly.Module>> {
   const modules: Record<string, WebAssembly.Module> = {}
-  for (const binding of wasmBindings) {
-    const module = await WebAssembly.compile(readFileSync(binding.filePath))
-    modules[binding.name] = module
-  }
+
+  await Promise.all(
+    wasmBindings.map(async (binding) => {
+      const module = await WebAssembly.compile(
+        await fs.readFile(binding.filePath)
+      )
+      modules[binding.name] = module
+    })
+  )
+
   return modules
 }