Use thread pool

langchain/callbacks/tracers/langchain.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 
 import logging
 import os
+from concurrent.futures import ThreadPoolExecutor
 from datetime import datetime
 from typing import Any, Dict, List, Optional
 from uuid import UUID
@@ -72,6 +73,9 @@ class LangChainTracer(BaseTracer):
         self.example_id = example_id
         self.session_name = session_name or os.getenv("LANGCHAIN_SESSION", "default")
         self.session_extra = session_extra
+        self._executor = ThreadPoolExecutor(
+            max_workers=5, thread_name_prefix="langchain_tracer"
+        )
 
     def on_chat_model_start(
         self,
@@ -151,4 +155,4 @@ class LangChainTracer(BaseTracer):
         """Persist a run."""
         run.reference_example_id = self.example_id
         # TODO: Post first then patch
-        self._persist_run_nested(run)
+        self._executor.submit(self._persist_run_nested, run)

tests/unit_tests/callbacks/tracers/test_tracer.py

@@ -98,6 +98,7 @@ def test_persist_run(
             lang_chain_tracer_v2.run_map[str(run.id)] = run
         for run in sample_runs:
             lang_chain_tracer_v2._end_trace(run)
+        lang_chain_tracer_v2._executor.shutdown(wait=True)
 
         assert post.call_count == 3
         assert get.call_count == 0