Ensure we chunk revalidate tag requests (#70189)

This ensures we chunk revalidate tag requests so we don't send too many
at once.

x-ref: [slack
thread](https://vercel.slack.com/archives/C03UR7US95F/p1726585656900449?thread_ts=1726049244.204009&cid=C03UR7US95F)

---------

Co-authored-by: Kelly Davis <[email protected]>

Author: ijjk

packages/next/src/server/lib/incremental-cache/fetch-cache.ts

@@ -176,29 +176,32 @@ export default class FetchCache implements CacheHandler {
       return
     }
 
-    try {
-      const res = await fetchRetryWithTimeout(
-        `${this.cacheEndpoint}/v1/suspense-cache/revalidate?tags=${tags
-          .map((tag) => encodeURIComponent(tag))
-          .join(',')}`,
-        {
-          method: 'POST',
-          headers: this.headers,
-          // @ts-expect-error not on public type
-          next: { internal: true },
-        }
-      )
+    for (let i = 0; i < Math.ceil(tags.length / 64); i++) {
+      const currentTags = tags.slice(i * 64, i * 64 + 64)
+      try {
+        const res = await fetchRetryWithTimeout(
+          `${this.cacheEndpoint}/v1/suspense-cache/revalidate?tags=${currentTags
+            .map((tag) => encodeURIComponent(tag))
+            .join(',')}`,
+          {
+            method: 'POST',
+            headers: this.headers,
+            // @ts-expect-error not on public type
+            next: { internal: true },
+          }
+        )
 
-      if (res.status === 429) {
-        const retryAfter = res.headers.get('retry-after') || '60000'
-        rateLimitedUntil = Date.now() + parseInt(retryAfter)
-      }
+        if (res.status === 429) {
+          const retryAfter = res.headers.get('retry-after') || '60000'
+          rateLimitedUntil = Date.now() + parseInt(retryAfter)
+        }
 
-      if (!res.ok) {
-        throw new Error(`Request failed with status ${res.status}.`)
+        if (!res.ok) {
+          throw new Error(`Request failed with status ${res.status}.`)
+        }
+      } catch (err) {
+        console.warn(`Failed to revalidate tag`, currentTags, err)
       }
-    } catch (err) {
-      console.warn(`Failed to revalidate tag ${tags}`, err)
     }
   }
 

test/production/app-dir/fetch-cache/app/api/revalidate-alot/route.ts

@@ -0,0 +1,11 @@
+import { revalidateTag } from 'next/cache'
+import { NextRequest, NextResponse } from 'next/server'
+
+export const dynamic = 'force-dynamic'
+
+export function GET(req: NextRequest) {
+  for (let i = 0; i < 130; i++) {
+    revalidateTag(`thankyounext-${i}`)
+  }
+  return NextResponse.json({ done: true })
+}

test/production/app-dir/fetch-cache/fetch-cache.test.ts

@@ -18,6 +18,7 @@ describe('fetch-cache', () => {
   let nextInstance: any
   let fetchGetReqIndex = 0
   let revalidateReqIndex = 0
+  let revalidateReqShouldTimeout = false
   let fetchGetShouldError = false
   let fetchCacheServer: http.Server
   let fetchCacheRequests: Array<{
@@ -101,6 +102,7 @@ describe('fetch-cache', () => {
     fetchCacheRequests = []
     storeCacheItems = false
     fetchGetShouldError = false
+    revalidateReqShouldTimeout = false
     fetchCacheServer = http.createServer(async (req, res) => {
       console.log(`fetch cache request ${req.url} ${req.method}`, req.headers)
       const parsedUrl = new URL(req.url || '/', 'http://n')
@@ -114,7 +116,8 @@ describe('fetch-cache', () => {
       if (parsedUrl.pathname === '/v1/suspense-cache/revalidate') {
         revalidateReqIndex += 1
         // timeout unless it's 3rd retry
-        const shouldTimeout = revalidateReqIndex % 3 !== 0
+        const shouldTimeout =
+          revalidateReqShouldTimeout && revalidateReqIndex % 3 !== 0
 
         if (shouldTimeout) {
           console.log('not responding for', req.url, { revalidateReqIndex })
@@ -220,10 +223,26 @@ describe('fetch-cache', () => {
   })
 
   it('should retry 3 times when revalidate times out', async () => {
-    await fetchViaHTTP(appPort, '/api/revalidate')
+    revalidateReqShouldTimeout = true
+    try {
+      await fetchViaHTTP(appPort, '/api/revalidate')
+
+      await retry(() => {
+        expect(revalidateReqIndex).toBe(3)
+      })
+      expect(cliOuptut).not.toContain('Failed to revalidate')
+      expect(cliOuptut).not.toContain('Error')
+    } finally {
+      revalidateReqShouldTimeout = false
+    }
+  })
+
+  it('should batch revalidate tag requests if > 64', async () => {
+    const revalidateReqIndexStart = revalidateReqIndex
+    await fetchViaHTTP(appPort, '/api/revalidate-alot')
 
     await retry(() => {
-      expect(revalidateReqIndex).toBe(3)
+      expect(revalidateReqIndex).toBe(revalidateReqIndexStart + 3)
     })
     expect(cliOuptut).not.toContain('Failed to revalidate')
     expect(cliOuptut).not.toContain('Error')

test/turbopack-build-tests-manifest.json

@@ -14633,7 +14633,8 @@
         "fetch-cache should have correct fetchUrl field for fetches and unstable_cache",
         "fetch-cache should not retry for failed fetch-cache GET",
         "fetch-cache should retry 3 times when revalidate times out",
-        "fetch-cache should update cache TTL even if cache data does not change"
+        "fetch-cache should update cache TTL even if cache data does not change",
+        "fetch-cache should batch revalidate tag requests if > 64"
       ],
       "pending": [],
       "flakey": [],