Fix/ Several steps waiting at the same lock, handler only released on…

[CodeDecree]

Description

So on investigation I found out that if stepwise is set to true, the execution goes under the _step_condition lock that is shared by every task. That lock is released by the handler via _step_condition.notify() in handler.py.

Now, if a step execution outputs an event that triggers more than one step/task, every task halts sharing the same lock, but the handler only releases one using notify(). And if there were multiple tasks waiting to be executed, only one of them executes.

Fix: I changed _step_condition.notify() to _step_condition.notify_all() so all the waiting tasks at that step get their execution.

Fixes #18334

New Package?

Did I fill in the tool.llamahub section in the pyproject.toml and provide a detailed README.md for my new integration or package?

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Version Bump?

Did I bump the version in the pyproject.toml file of the package I am updating? (Except for the llama-index-core package)

• Yes
• No

Type of Change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

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• I added new unit tests to cover this change
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Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added Google Colab support for the newly added notebooks.
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I ran make format; make lint to appease the lint gods

[logan-markewich]

@CodeDecree doesn't this break the concept of stepwise execution? If multiple steps are waiting to run, they should run one at a time right?

(being completely honest, this feature has been a bit of a nightmare to implement/maintain, and I lean heavily towards ripping it out -- curious if you had an actual use-case for this?)

[CodeDecree]

@logan-markewich Ah, yes, you are right. If one step triggers multiple tasks, then all those will go concurrently.

Maybe we can call _step_condition.notify() an equal number of times to the len(await self.ctx.running_steps()) in the handler but I do believe it might have its own repercussions. I can try to fix that and probably add the test cases for the same.

I never used this feature myself. I was just going through the repo, exploring some issues, trying to contribute. Anyways, 'ripping it out' sounds like a pretty cool PR.