Merge pull request 'Run image decoding and resizing off the event loop' (#75) from perf/offload-image-processing into main

tests/unit/test_file_upload.py

@@ -1,6 +1,7 @@
 """Tests for conversation file attachments: extraction, /upload and stream-query file_key."""
 
 import io
+import threading
 from datetime import timedelta
 from types import SimpleNamespace
 from unittest.mock import AsyncMock, patch
@@ -190,6 +191,21 @@ class TestUploadRoute:
         s3.upload_image.assert_awaited_once()
         s3.upload_file.assert_not_awaited()
 
+    async def test_image_processing_runs_off_the_event_loop(
+        self, app, headers, s3, monkeypatch
+    ):
+        threads = []
+        real = conv.process_image
+
+        def recording(*args):
+            threads.append(threading.current_thread())
+            return real(*args)
+
+        monkeypatch.setattr(conv, "process_image", recording)
+        resp = await _upload(app, headers, _png_bytes(), "cat.png", "image/png")
+        assert resp.status_code == 200
+        assert threads and threads[0] is not threading.main_thread()
+
     async def test_unsupported_type_is_415(self, app, headers, s3):
         resp = await _upload(app, headers, b"PK\x03\x04", "a.zip", "application/zip")
         assert resp.status_code == 415