feat: add experiment for sharpjs cpu flags (#71733)

This PR adds two experimental flags to configure sharpjs settings that
may improve cpu for image optimization.

packages/next/src/server/config-schema.ts

@@ -314,6 +314,9 @@ export const configSchema: zod.ZodType<NextConfig> = z.lazy(() =>
         forceSwcTransforms: z.boolean().optional(),
         fullySpecified: z.boolean().optional(),
         gzipSize: z.boolean().optional(),
+        imgOptConcurrency: z.number().int().optional().nullable(),
+        imgOptTimeoutInSeconds: z.number().int().optional(),
+        imgOptMaxInputPixels: z.number().int().optional(),
         internal_disableSyncDynamicAPIWarnings: z.boolean().optional(),
         isrFlushToDisk: z.boolean().optional(),
         largePageDataBytes: z.number().optional(),

packages/next/src/server/config-shared.ts

@@ -286,6 +286,9 @@ export interface ExperimentalConfig {
   extensionAlias?: Record<string, any>
   allowedRevalidateHeaderKeys?: string[]
   fetchCacheKeyPrefix?: string
+  imgOptConcurrency?: number | null
+  imgOptTimeoutInSeconds?: number
+  imgOptMaxInputPixels?: number
   optimisticClientCache?: boolean
   /**
    * @deprecated use config.expireTime instead
@@ -1112,6 +1115,9 @@ export const defaultConfig: NextConfig = {
         (os.cpus() || { length: 1 }).length) - 1
     ),
     memoryBasedWorkersCount: false,
+    imgOptConcurrency: null,
+    imgOptTimeoutInSeconds: 7,
+    imgOptMaxInputPixels: 268_402_689, // https://sharp.pixelplumbing.com/api-constructor#:~:text=%5Boptions.limitInputPixels%5D
     isrFlushToDisk: true,
     workerThreads: false,
     proxyTimeout: undefined,

packages/next/src/server/image-optimizer.ts

@@ -47,7 +47,7 @@ const BLUR_QUALITY = 70 // should match `next-image-loader`
 
 let _sharp: typeof import('sharp')
 
-function getSharp() {
+function getSharp(concurrency: number | null | undefined) {
   if (_sharp) {
     return _sharp
   }
@@ -59,7 +59,7 @@ function getSharp() {
       // https://sharp.pixelplumbing.com/api-utility#concurrency
       const divisor = process.env.NODE_ENV === 'development' ? 4 : 2
       _sharp.concurrency(
-        Math.floor(Math.max(_sharp.concurrency() / divisor, 1))
+        concurrency ?? Math.floor(Math.max(_sharp.concurrency() / divisor, 1))
       )
     }
   } catch (e: unknown) {
@@ -512,15 +512,27 @@ export async function optimizeImage({
   quality,
   width,
   height,
+  concurrency,
+  limitInputPixels,
+  timeoutInSeconds,
 }: {
   buffer: Buffer
   contentType: string
   quality: number
   width: number
   height?: number
+  concurrency?: number | null
+  limitInputPixels?: number
+  timeoutInSeconds?: number
 }): Promise<Buffer> {
-  const sharp = getSharp()
-  const transformer = sharp(buffer).timeout({ seconds: 7 }).rotate()
+  const sharp = getSharp(concurrency)
+  const transformer = sharp(buffer, {
+    limitInputPixels,
+  })
+    .timeout({
+      seconds: timeoutInSeconds ?? 7,
+    })
+    .rotate()
 
   if (height) {
     transformer.resize(width, height)
@@ -631,6 +643,10 @@ export async function imageOptimizer(
     'href' | 'width' | 'quality' | 'mimeType'
   >,
   nextConfig: {
+    experimental: Pick<
+      NextConfigComplete['experimental'],
+      'imgOptConcurrency' | 'imgOptMaxInputPixels' | 'imgOptTimeoutInSeconds'
+    >
     images: Pick<
       NextConfigComplete['images'],
       'dangerouslyAllowSVG' | 'minimumCacheTTL'
@@ -735,6 +751,9 @@ export async function imageOptimizer(
       contentType,
       quality,
       width,
+      concurrency: nextConfig.experimental.imgOptConcurrency,
+      limitInputPixels: nextConfig.experimental.imgOptMaxInputPixels,
+      timeoutInSeconds: nextConfig.experimental.imgOptTimeoutInSeconds,
     })
     if (optimizedBuffer) {
       if (isDev && width <= BLUR_IMG_SIZE && quality === BLUR_QUALITY) {

test/integration/image-optimizer/test/index.test.ts

@@ -734,6 +734,37 @@ describe('Image Optimizer', () => {
     })
   })
 
+  describe('experimental.imgOptMaxInputPixels in next.config.js', () => {
+    let app
+    let appPort
+
+    beforeAll(async () => {
+      nextConfig.replace(
+        '{ /* replaceme */ }',
+        JSON.stringify({
+          experimental: {
+            imgOptMaxInputPixels: 100,
+          },
+        })
+      )
+      await cleanImagesDir({ imagesDir })
+      appPort = await findPort()
+      app = await launchApp(appDir, appPort)
+    })
+    afterAll(async () => {
+      await killApp(app)
+      nextConfig.restore()
+    })
+    it('should fallback to source image when input exceeds imgOptMaxInputPixels', async () => {
+      const size = 256 // defaults defined in lib/image-config.ts
+      const query = { w: size, q: 75, url: '/test.jpg' }
+      const opts = { headers: { accept: 'image/webp' } }
+      const res = await fetchViaHTTP(appPort, '/_next/image', query, opts)
+      expect(res.status).toBe(200)
+      expect(res.headers.get('Content-Type')).toBe('image/jpeg')
+    })
+  })
+
   describe('External rewrite support with for serving static content in images', () => {
     ;(process.env.TURBOPACK_DEV ? describe.skip : describe)(
       'production mode',