From 453f5052569dafb52e82e875a8976cf348ed16d4 Mon Sep 17 00:00:00 2001
From: Szymon Chmal <szymonchmal@gmail.com>
Date: Tue, 14 Jan 2025 21:23:42 +0100
Subject: [PATCH] [DevTools] Prevent crash when starting consecutive profiling
 sessions (#32066)

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## Summary

This pull request resolves an issue where consecutive profiling sessions
would cause Dev Tools to freeze due to an infinite loop of state
updates. The problem occurs when the startProfiling function triggers a
call to [`selectCommitIndex(0)` in
SnapshotSelector](https://github.com/facebook/react/blob/b3a95caf61bc716fb618997e6e9f3a0c8c9c8374/packages/react-devtools-shared/src/devtools/views/Profiler/SnapshotSelector.js#L77-L85)
as previous profiling data is available, which causes a re-render. Then,
[ProfilerContextProvider calls
`selectCommitIndex(null)`](https://github.com/facebook/react/blob/b3a95caf61bc716fb618997e6e9f3a0c8c9c8374/packages/react-devtools-shared/src/devtools/views/Profiler/ProfilerContext.js#L231-L241)
to clear the view while profiling is in progress, leading to another
re-render and creating an infinite loop. This behavior was prevented by
clearing the existing profiling data before starting a new session.

Closes #31977
Closes #31679

## How did you test this change?

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I ran the Dev Tools locally following [the contributing
guideline](https://github.com/facebook/react/blob/b3a95caf61bc716fb618997e6e9f3a0c8c9c8374/packages/react-devtools/CONTRIBUTING.md).
I observed the freeze at the start of the second profiling session.
Then, I modified the code to clear the store when starting a new session
and ran the Dev Tools again. This time, no freeze was observed.

Before:

https://github.com/user-attachments/assets/9d790f84-f6d0-4951-8202-e599cf8d225b

After:

https://github.com/user-attachments/assets/af097019-0b8f-49dd-8afc-0f6cd72af787
---
 packages/react-devtools-shared/src/devtools/ProfilerStore.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/react-devtools-shared/src/devtools/ProfilerStore.js b/packages/react-devtools-shared/src/devtools/ProfilerStore.js
index b9bbdb11df..33240bd77f 100644
--- a/packages/react-devtools-shared/src/devtools/ProfilerStore.js
+++ b/packages/react-devtools-shared/src/devtools/ProfilerStore.js
@@ -191,6 +191,8 @@ export default class ProfilerStore extends EventEmitter<{
   }
 
   startProfiling(): void {
+    this.clear();
+
     this._bridge.send('startProfiling', {
       recordChangeDescriptions: this._store.recordChangeDescriptions,
       recordTimeline: this._store.supportsTimeline,