[ASTextNode] Fix a deadlock that could occur when enabling experimental ASTextNode2 via ASConfiguration #903
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
…al ASTextNode2 via ASConfiguration Because multiple threads can enter this allocWithZone: method around the same time, it is possible for one of them to setSuperclass first, and then the second thread would get stuck in an infinite loop. When climbing the inheritance heirarchy, ASTextNode2 would be encountered by this second thread, and it would continue until reaching c == Nil. Since there was no case to catch this, an infinite loop would result. Then the main thread can be deadlocked if a method like waitUntilAllUpdatesAreProcessed is called on ASCollectionView.
|
🚫 CI failed with log |
|
Failure looks spurious - any way to re-run? Tests pass locally. |
Generated by 🚫 Danger |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Because multiple threads can enter this allocWithZone: method around the same time, it is possible for one of them to setSuperclass first, and then the second thread would get stuck in an infinite loop.
When climbing the inheritance hierarchy, ASTextNode2 would be encountered by this second thread, and it would continue until reaching c == Nil. Since there was no case to catch this, an infinite loop would result.
Then the main thread can be deadlocked if a method like waitUntilAllUpdatesAreProcessed is called on ASCollectionView.