opentelemetry-instrumentation-django: fix spans ending prematurely for StreamingHttpResponse

[SurbhiD404]

Description

Fixes #4681

The Django instrumentation middleware ends the request span synchronously inside process_response(), right after get_response() returns. For a normal HttpResponse this is correct, since the body is fully rendered by that point.

For StreamingHttpResponse, however, get_response() returns before the stream is actually consumed. Django (and WSGI servers) only iterate response.streaming_content afterward, once the response is being sent to the client. As a result, the span's end_time is set before the streamed content has finished sending, producing inaccurate span durations for streaming endpoints.

For streaming responses (response.streaming), span completion is now deferred until response.close() is called, which occurs after the stream has been consumed. Existing behavior for non-streaming responses and exception paths is preserved.

Scope: this change covers the synchronous (WSGI) path only. Async/ASGI behavior remains unchanged.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Added TestMiddlewareStreamingResponse in tests/test_middleware.py.

The test records the order of:

• streaming content consumption
• span completion (Span.end)

and verifies that the span is not completed before the streaming response is consumed.

Tested locally with:

tox -e py313-test-instrumentation-django-3

Result:

78 passed

Does This PR Require a Core Repo Change?

• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: SurbhiD404 / name: Surbhi Dharvan (b98cc22)

[SurbhiD404]

Hi @xrmx,

When you get a chance, I'd appreciate a review of this PR. It fixes premature span completion for Django StreamingHttpResponse and includes a regression test and changelog fragment.

Happy to address any feedback. Thanks!