Prevent stackoverflow #23
Merged
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
TwitchBronBron
commented
Oct 17, 2024
| @@ -251,7 +251,13 @@ namespace promises.internal | |||
| if storage = invalid then | |||
| ' unregister any observers on the promise to prevent multiple callbacks | |||
| promises.internal.unobserveFieldScoped(promise, promises.internal.PromiseField.promiseState) | |||
| promises.internal.observeFieldScoped(promise, promises.internal.PromiseField.promiseState, promises.internal.notifyListeners) | |||
| promises.internal.observeFieldScoped(promise, promises.internal.PromiseField.promiseState, sub(event) | |||
There was a problem hiding this comment.
This was the important piece here. This observer fires synchronously, which would then trigger upstream promises to also trigger synchronously (since they were all already marked resolved).
By adding a nexttick, it allows each promise's observers to run nexttick, breaking the stack chain.
TwitchBronBron
commented
Oct 17, 2024
| @@ -482,7 +488,7 @@ namespace promises.internal | |||
| print "Crash during utils.delay:", e | |||
| #end if | |||
| end try | |||
| m[delayId] = invalid | |||
| m.delete(delayId) | |||
There was a problem hiding this comment.
Unrelated to the main issue. I noticed these timer entries were never getting properly cleaned up, as they were only being set to invalid. This should clean up the m variable nicely now.
markwpearce
approved these changes
Oct 17, 2024
iObject
approved these changes
Oct 17, 2024
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Outdated suggestions cannot be applied.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.
Fixes an issue where deeply nested promise chain could cause a stackoverflow. This seems to be caused by the observers all firing synchronously, so when the lowest promise unravels, it synchronously triggers observers the entire way back up.
I added a test that proves we can now successfully unravel a promise chain 10,000 promises deep (but I suspect there is no limitation now in our implementation other than max memory usage).