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Project	Deployment	Actions	Updated (UTC)
litellm	Ready	Preview, Comment	Mar 16, 2026 11:32am

All committers have signed the CLA.

Merging this PR will not alter performance

✅ 16 untouched benchmarks

_{Comparing pandego:fix/langsmith-sync-no-event-loop (59caea4) with main (58e74a6)}

Greptile Summary

This PR fixes a RuntimeError: no running event loop crash that occurred when LangsmithLogger was instantiated from a synchronous context. The unconditional asyncio.create_task(self.periodic_flush()) call in __init__ is replaced with a guarded _start_periodic_flush_task() helper that uses asyncio.get_running_loop(), returning None (and logging a debug message) when no loop is present. To ensure the flush task still starts when the logger is later used asynchronously, _ensure_periodic_flush_task() is called at the top of both async_log_success_event and async_log_failure_event, lazily scheduling the task on the first async invocation after a sync-context init.

Key observations:

• The fix correctly handles the sync-init → async-use production pattern that was previously broken.
• _ensure_periodic_flush_task is synchronous with no await between its guard check and assignment, which correctly prevents duplicate task creation under asyncio's cooperative scheduling model.
• The synchronous log_success_event path intentionally does not call _ensure_periodic_flush_task; it relies on batch-size flushing via _send_batch(), which is the correct design since periodic flush is an async-only concept here.
• All stale @patch("asyncio.create_task") decorators (which patched the wrong symbol) have been removed and replaced with focused, accurate test coverage for the guard paths and lazy startup.
• Previous review feedback (silent queue drops on sync-init, placement of _ensure_periodic_flush_task inside the try block for async_log_failure_event, loose call-count assertions, and missing failure-event test) has been fully addressed in this iteration.

Confidence Score: 4/5

• This PR is safe to merge; it fixes a real crash path without breaking existing async behaviour.
• The core logic change is minimal and well-targeted. All previously raised review threads have been addressed. Test coverage now spans the no-loop, with-loop, and lazy-startup paths for both async log methods. The only reason for a non-perfect score is a small untested edge case: _ensure_periodic_flush_task will re-invoke _start_periodic_flush_task on every async log call when the prior task's done() is True (e.g., after a periodic_flush coroutine dies due to an unhandled exception) — but this is intentional recovery behaviour, is safe under asyncio's cooperative model, and is documented in a comment.
• No files require special attention; both changed files are straightforward.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[LangsmithLogger.__init__] --> B[self._flush_task = _start_periodic_flush_task]
    B --> C{asyncio.get_running_loop?}
    C -- RuntimeError: No Loop --> D[return None\n_flush_task = None]
    C -- Loop exists --> E[loop.create_task periodic_flush\n_flush_task = Task]

    F[async_log_success_event] --> G[_ensure_periodic_flush_task]
    H[async_log_failure_event] --> G
    G --> I{_flush_task is None\nor .done?}
    I -- Yes --> J[_start_periodic_flush_task]
    J --> C
    I -- No --> K[Task already running - skip]

    E --> L[periodic_flush loop\n while True: sleep → flush_queue]
    D -.->|lazy start on first async call| F
    D -.->|lazy start on first async call| H

_{Last reviewed commit: 59caea4}

Addressed the review feedback in the latest push.

What changed:

• lazily start the periodic flush task on async log calls if the logger was created before an event loop existed
• keep the original init-time guard so sync construction no longer raises
• strengthened the tests:
  • verify the no-loop init path leaves _flush_task unset
  • verify the happy path schedules loop.create_task(...)
  • verify async logging lazily starts the periodic flush task after sync init
• removed the stale @patch("asyncio.create_task") decorators from the init tests

I also checked branch state against main before pushing - it is current, so the earlier failing checks were not caused by the branch being behind.

Local validation run:

• uv run pytest tests/test_litellm/integrations/test_langsmith_init.py -q
• uv run pytest tests/logging_callback_tests/test_langsmith_unit_test.py -q

Quick note: the LangSmith sync-init fix and regression coverage are updated per review and passing locally.

The remaining red checks appear unrelated to this change:

• lint
• test (proxy-misc)

I did not change the proxy startup path touched by the proxy-misc failure, and the lint failure looks repo-wide rather than specific to the LangSmith files in this PR.