fix: update devtools-frontend (#125)

Author: nolanlawson

scripts/devtools.rollup.config.js

@@ -43,6 +43,7 @@ export default {
       __entry__: `
         export { HeapSnapshotLoader } from './front_end/entrypoints/heap_snapshot_worker/heap_snapshot_worker.ts'
         export { HeapSnapshotModel } from './front_end/models/heap_snapshot_model/heap_snapshot_model.ts'
+        export { SecondaryInitManager } from './front_end/entrypoints/heap_snapshot_worker/HeapSnapshot.ts'
       `,
       // Promise.withResolvers minimal shim
       // TODO: remove when we set our minimum Node to v22+

src/metrics/heapsnapshots/heapsnapshots.js

@@ -2,7 +2,10 @@ import path from 'node:path'
 import { createReadStream, createWriteStream } from 'node:fs'
 import { realpath } from 'node:fs/promises'
 import { tmpdir } from 'node:os'
-import { HeapSnapshotLoader } from '../../thirdparty/devtools-frontend/index.js'
+import {
+  HeapSnapshotLoader,
+  SecondaryInitManager
+} from '../../thirdparty/devtools-frontend/index.js'
 import { randomUUID } from 'node:crypto'
 
 // via https://github.com/sindresorhus/temp-dir/blob/437937c/index.js#L4
@@ -54,5 +57,19 @@ export async function createHeapSnapshotModel (filename) {
   loader.close()
   await loader.parsingComplete
 
-  return (await loader.buildSnapshot())
+  // Pattern borrowed from `createJSHeapSnapshotForTesting` in Chromium code.
+  // https://github.com/ChromeDevTools/devtools-frontend/blob/866e7ab/front_end/entrypoints/heap_snapshot_worker/HeapSnapshot.ts#L3675-L3682
+  // Rather than trying to make it work with two workers, we just do it all in one thread.
+  // For context see this commit splitting the work into two workers:
+  // https://github.com/ChromeDevTools/devtools-frontend/commit/6a523a7
+  const channel = new MessageChannel()
+  try {
+    // eslint-disable-next-line no-new
+    new SecondaryInitManager(channel.port2)
+    return await loader.buildSnapshot(channel.port1)
+  } finally {
+    // Without this, the Node process will just hang forever
+    channel.port1.close()
+    channel.port2.close()
+  }
 }