Limit concurrent open files during 'npm cache verify'

lib/entry-index.js

@@ -19,6 +19,10 @@ const hashToSegments = require('./util/hash-to-segments')
 const indexV = require('../package.json')['cache-version'].index
 const { moveFile } = require('@npmcli/fs')
 
+const pMap = require('p-map')
+const lsStreamConcurrency = 5
+
+
 module.exports.NotFoundError = class NotFoundError extends Error {
   constructor (cache, key) {
     super(`No cache entry for ${key} found in ${cache}`)
@@ -182,15 +186,15 @@ function lsStream (cache) {
   // Set all this up to run on the stream and then just return the stream
   Promise.resolve().then(async () => {
     const buckets = await readdirOrEmpty(indexDir)
-    await Promise.all(buckets.map(async (bucket) => {
+    await pMap(buckets, async (bucket) => {
       const bucketPath = path.join(indexDir, bucket)
       const subbuckets = await readdirOrEmpty(bucketPath)
-      await Promise.all(subbuckets.map(async (subbucket) => {
+      await pMap(subbuckets, async (subbucket) => {
         const subbucketPath = path.join(bucketPath, subbucket)
 
         // "/cachename/<bucket 0xFF>/<bucket 0xFF>./*"
         const subbucketEntries = await readdirOrEmpty(subbucketPath)
-        await Promise.all(subbucketEntries.map(async (entry) => {
+        await pMap(subbucketEntries, async (entry) => {
           const entryPath = path.join(subbucketPath, entry)
           try {
             const entries = await bucketEntries(entryPath)
@@ -213,9 +217,12 @@ function lsStream (cache) {
             }
             throw err
           }
-        }))
-      }))
-    }))
+        },
+        { concurrency: lsStreamConcurrency })
+      },
+      { concurrency: lsStreamConcurrency })
+    },
+    { concurrency: lsStreamConcurrency })
     stream.end()
     return stream
   }).catch(err => stream.emit('error', err))