fix(flask): use try/finally for active_requests decrement per review

Signed-off-by: alliasgher <alliasgher123@gmail.com>

Author: alliasgher

instrumentation/opentelemetry-instrumentation-flask/src/opentelemetry/instrumentation/flask/__init__.py

@@ -417,50 +417,48 @@ def _start_response(status, response_headers, *args, **kwargs):
 
         try:
             result = wsgi_app(wrapped_app_environ, _start_response)
-        except Exception:
-            active_requests_counter.add(-1, active_requests_count_attrs)
-            raise
-
-        # Note: Streaming response context cleanup is now handled in the Flask teardown function
-        # (_wrapped_teardown_request) to ensure proper cleanup following Logfire's recommendations
-        # for OpenTelemetry generator context management
-
-        if should_trace:
-            duration_s = default_timer() - start
-            # Get the span from wrapped_app_environ and re-create context manually
-            # to pass to histogram for exemplars generation
-            span = wrapped_app_environ.get(_ENVIRON_SPAN_KEY)
-            metrics_context = trace.set_span_in_context(span)
-
-            if duration_histogram_old:
-                duration_attrs_old = otel_wsgi._parse_duration_attrs(
-                    attributes, _StabilityMode.DEFAULT
-                )
 
-                if request_route:
-                    # http.target to be included in old semantic conventions
-                    duration_attrs_old[HTTP_TARGET] = str(request_route)
-                duration_histogram_old.record(
-                    max(round(duration_s * 1000), 0),
-                    duration_attrs_old,
-                    context=metrics_context,
-                )
-            if duration_histogram_new:
-                duration_attrs_new = otel_wsgi._parse_duration_attrs(
-                    attributes, _StabilityMode.HTTP
-                )
+            # Note: Streaming response context cleanup is now handled in the Flask teardown function
+            # (_wrapped_teardown_request) to ensure proper cleanup following Logfire's recommendations
+            # for OpenTelemetry generator context management
 
-                if request_route:
-                    duration_attrs_new[HTTP_ROUTE] = str(request_route)
+            if should_trace:
+                duration_s = default_timer() - start
+                # Get the span from wrapped_app_environ and re-create context manually
+                # to pass to histogram for exemplars generation
+                span = wrapped_app_environ.get(_ENVIRON_SPAN_KEY)
+                metrics_context = trace.set_span_in_context(span)
+
+                if duration_histogram_old:
+                    duration_attrs_old = otel_wsgi._parse_duration_attrs(
+                        attributes, _StabilityMode.DEFAULT
+                    )
 
-                duration_histogram_new.record(
-                    max(duration_s, 0),
-                    duration_attrs_new,
-                    context=metrics_context,
-                )
+                    if request_route:
+                        # http.target to be included in old semantic conventions
+                        duration_attrs_old[HTTP_TARGET] = str(request_route)
+                    duration_histogram_old.record(
+                        max(round(duration_s * 1000), 0),
+                        duration_attrs_old,
+                        context=metrics_context,
+                    )
+                if duration_histogram_new:
+                    duration_attrs_new = otel_wsgi._parse_duration_attrs(
+                        attributes, _StabilityMode.HTTP
+                    )
+
+                    if request_route:
+                        duration_attrs_new[HTTP_ROUTE] = str(request_route)
 
-        active_requests_counter.add(-1, active_requests_count_attrs)
-        return result
+                    duration_histogram_new.record(
+                        max(duration_s, 0),
+                        duration_attrs_new,
+                        context=metrics_context,
+                    )
+
+            return result
+        finally:
+            active_requests_counter.add(-1, active_requests_count_attrs)
 
     def _should_trace(excluded_urls) -> bool:
         return bool(