Disconnect gRPC client stub when shutting down OTLPSpanExporter

CHANGELOG.md

@@ -14,6 +14,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#4402](https://github.com/open-telemetry/opentelemetry-python/pull/4402))
 - Tolerates exceptions when loading resource detectors via `OTEL_EXPERIMENTAL_RESOURCE_DETECTORS`
   ([#4373](https://github.com/open-telemetry/opentelemetry-python/pull/4373))
+- Disconnect gRPC client stub when shutting down `OTLPSpanExporter`
+  ([#4370](https://github.com/open-telemetry/opentelemetry-python/pull/4370))
 - opentelemetry-sdk: fix OTLP exporting of Histograms with explicit buckets advisory
   ([#4434](https://github.com/open-telemetry/opentelemetry-python/pull/4434))
 - opentelemetry-exporter-otlp-proto-grpc: better dependency version range for Python 3.13

exporter/opentelemetry-exporter-otlp-proto-grpc/src/opentelemetry/exporter/otlp/proto/grpc/exporter.py

@@ -243,8 +243,8 @@ def __init__(
         ) or Compression.NoCompression
 
         if insecure:
-            self._client = self._stub(
-                insecure_channel(self._endpoint, compression=compression)
+            self._channel = insecure_channel(
+                self._endpoint, compression=compression
             )
         else:
             credentials = _get_credentials(
@@ -253,11 +253,10 @@ def __init__(
                 OTEL_EXPORTER_OTLP_CLIENT_KEY,
                 OTEL_EXPORTER_OTLP_CLIENT_CERTIFICATE,
             )
-            self._client = self._stub(
-                secure_channel(
-                    self._endpoint, credentials, compression=compression
-                )
+            self._channel = secure_channel(
+                self._endpoint, credentials, compression=compression
             )
+        self._client = self._stub(self._channel)
 
         self._export_lock = threading.Lock()
         self._shutdown = False
@@ -360,6 +359,7 @@ def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
         # wait for the last export if any
         self._export_lock.acquire(timeout=timeout_millis / 1e3)
         self._shutdown = True
+        self._channel.close()
         self._export_lock.release()
 
     @property