Share client in evaluation callback (#7807)

Guarantee the evaluator traces go to same endpoint

langchain/callbacks/manager.py

@@ -7,6 +7,7 @@ import os
 from contextlib import asynccontextmanager, contextmanager
 from contextvars import ContextVar
 from typing import (
+    TYPE_CHECKING,
     Any,
     AsyncGenerator,
     Dict,
@@ -45,6 +46,9 @@ from langchain.schema import (
 )
 from langchain.schema.messages import BaseMessage, get_buffer_string
 
+if TYPE_CHECKING:
+    from langsmith import Client as LangSmithClient
+
 logger = logging.getLogger(__name__)
 Callbacks = Optional[Union[List[BaseCallbackHandler], BaseCallbackManager]]
 
@@ -144,6 +148,7 @@ def tracing_v2_enabled(
     *,
     example_id: Optional[Union[str, UUID]] = None,
     tags: Optional[List[str]] = None,
+    client: Optional[LangSmithClient] = None,
 ) -> Generator[None, None, None]:
     """Instruct LangChain to log all runs in context to LangSmith.
 
@@ -168,6 +173,7 @@ def tracing_v2_enabled(
         example_id=example_id,
         project_name=project_name,
         tags=tags,
+        client=client,
     )
     tracing_v2_callback_var.set(cb)
     yield

langchain/callbacks/tracers/evaluation.py

@@ -10,6 +10,7 @@ from langsmith import Client, RunEvaluator
 
 from langchain.callbacks.manager import tracing_v2_enabled
 from langchain.callbacks.tracers.base import BaseTracer
+from langchain.callbacks.tracers.langchain import _get_client
 from langchain.callbacks.tracers.schemas import Run
 
 logger = logging.getLogger(__name__)
@@ -77,7 +78,7 @@ class EvaluatorCallbackHandler(BaseTracer):
         self.example_id = (
             UUID(example_id) if isinstance(example_id, str) else example_id
         )
-        self.client = client or Client()
+        self.client = client or _get_client()
         self.evaluators = evaluators
         self.executor = ThreadPoolExecutor(
             max_workers=max(max_workers or len(evaluators), 1)
@@ -102,7 +103,9 @@ class EvaluatorCallbackHandler(BaseTracer):
         try:
             if self.project_name is None:
                 self.client.evaluate_run(run, evaluator)
-            with tracing_v2_enabled(project_name=self.project_name, tags=["eval"]):
+            with tracing_v2_enabled(
+                project_name=self.project_name, tags=["eval"], client=self.client
+            ):
                 self.client.evaluate_run(run, evaluator)
         except Exception as e:
             logger.error(