langchain

ba6c2590 - fix(core): prevent async task garbage collection (RUF006) (#34238)

fix(core): prevent async task garbage collection (RUF006) (#34238) # PR Title: fix(core): prevent async task garbage collection (RUF006) ## Description This PR addresses a cryptic issue (flagged by Ruff rule RUF006) where `asyncio` tasks created via `loop.create_task` could be garbage collected mid-execution because no strong reference was maintained. In `libs/core/langchain_core/language_models/llms.py`, the retry decorator's `_before_sleep` hook creates a fire-and-forget task for logging/callbacks. If the garbage collector runs before this task completes, the task may be destroyed, leading to silent failures. ## Changes - Introduced a module-level set `_background_tasks` to hold strong references to running tasks. - Updated `_before_sleep` to add new tasks to this set. - Added a `done_callback` to remove the task from the set upon completion, preventing memory leaks. ## Verification - Verified logic with a standalone script to ensure tasks are added/removed from the set correctly. - This is a standard pattern recommended in the Python `asyncio` documentation. ## Checklist - [x] I have read the contributing guidelines. - [x] I have run tests locally (logic verification). --------- Co-authored-by: Mason Daugherty <mason@langchain.dev> Co-authored-by: Mason Daugherty <github@mdrxy.com> Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>