Fixing 'active_steps' getting mixed in async operations

[emersonqueiroz]

Problem
I noticed that some steps were being assigned to the wrong threads, as shown in the screenshot below. After investigating the implementation, I discovered that the active_steps_var ContextVar was sometimes being mixed during parallel executions.

This issue seems similar to the common Python gotcha where using mutable objects as default values can lead to unexpected behavior. Specifically, it's not safe to use mutable objects as the default value for ContextVars in the current implementation:

Solution
Use a non-mutable default value (such as None) for the ContextVar and provide an empty list when retrieving its value. This approach prevents the mixing of ContextVars during parallel executions.

active_steps_var = ContextVar[List["Step"]]("active_steps", default=None)
active_steps_var.get([])  # Provide an empty list as the default value when getting the variable

Code examples

• Current ContextVar implementation leading to incorrect results
• Fixed ContextVar implementation
• Sample code using LiteralAI where the screenshot was obtained

[willydouhard]

Thank you for opening this, I ended up opening #165 which is inspired by this PR.

[emersonqueiroz]

Hi @willydouhard, I tested it and it seems to be working, thanks!