[web] speed up CI: bin-pack module acceptance tests (#35965)

GitOrigin-RevId: 92a33b4531d541c676018b3152c7abf74edd2eec

services/web/test/acceptance/getModuleTargets.js

@@ -1,13 +1,47 @@
 /* eslint-disable no-console */
 // silence settings module
 console.log = function () {}
+const fs = require('fs')
+const path = require('path')
 const Settings = require('@overleaf/settings')
 
 const MODULES = Settings.moduleImportSequence
-const TARGET = process.argv.slice(2).pop() || 'test_acceptance'
+const [TARGET = 'test_acceptance', shardIndexArg, shardTotalArg] =
+  process.argv.slice(2)
+
+let names = MODULES
+if (shardIndexArg && shardTotalArg) {
+  const shardIndex = parseInt(shardIndexArg, 10)
+  const shardTotal = parseInt(shardTotalArg, 10)
+  const timingsPath = path.join(__dirname, 'module-timings.json')
+  const timings = fs.existsSync(timingsPath)
+    ? JSON.parse(fs.readFileSync(timingsPath, 'utf8'))
+    : []
+  const msByName = new Map(timings.map(({ name, ms }) => [name, ms]))
+
+  // Greedy LPT (longest processing time first) bin-packing: sort modules by
+  // descending time, then drop each one into whichever shard currently has
+  // the smallest total, for a roughly time-fair split of work across shards.
+  const shards = Array.from({ length: shardTotal }, () => ({
+    totalMs: 0,
+    names: [],
+  }))
+  const sortedByMsDesc = MODULES.slice().sort(
+    (a, b) => (msByName.get(b) || 0) - (msByName.get(a) || 0)
+  )
+  for (const name of sortedByMsDesc) {
+    const shard = shards.reduce((lightest, s) =>
+      s.totalMs < lightest.totalMs ? s : lightest
+    )
+    shard.names.push(name)
+    shard.totalMs += msByName.get(name) || 0
+  }
+  names = shards[shardIndex - 1].names
+}
 
 if (TARGET === '--name-only') {
-  console.debug(MODULES.join('\n'))
+  console.debug(names.join('\n'))
 } else {
-  console.debug(MODULES.map(name => `modules/${name}/${TARGET}`).join('\n'))
+  const targets = names.map(name => `modules/${name}/${TARGET}`)
+  console.debug(targets.length > 0 ? targets.join('\n') : 'no_more_targets')
 }