add debug prints

python/lsst/daf/butler/remote_butler/server/handlers/_external_query.py

@@ -71,12 +71,15 @@ def query_execute(
     with ExitStack() as exit_stack:
         ctx = exit_stack.enter_context(_get_query_context(factory, request.query))
         spec = request.result_spec.to_result_spec(ctx.driver.universe)
+        print("before execute")
         response_pages = ctx.driver.execute(spec, ctx.tree)
 
         # We write the response incrementally, one page at a time, as
         # newline-separated chunks of JSON.  This allows clients to start
         # reading results earlier and prevents the server from exhausting
         # all its memory buffering rows from large queries.
+
+        print("before stream")
         output_generator = _stream_query_pages(
             # Transfer control of the context manager to
             # _stream_query_pages.
@@ -114,11 +117,13 @@ async def _stream_query_pages(
     When it takes longer than 15 seconds to get a response from the DB,
     sends a keep-alive message to prevent clients from timing out.
     """
+    print("in stream")
     # Ensure that the database connection is cleaned up by taking control of
     # exit_stack.
     async with contextmanager_in_threadpool(exit_stack):
         iterator = iterate_in_threadpool(serialize_query_pages(spec, pages))
         done = False
+        print("starting iteration")
         while not done:
             # Read the next value from the iterator, possibly with some
             # additional keep-alive messages if it takes a long time.
@@ -140,12 +145,15 @@ async def _fetch_next_with_keepalives(iterator: AsyncIterator[str]) -> AsyncIter
         future = asyncio.ensure_future(anext(iterator, None))
         ready = False
         while not ready:
+            print("waiting for task")
             (finished_task, pending_task) = await asyncio.wait([future], timeout=15)
             if pending_task:
+                print("timeout")
                 # Hit the timeout, send a keep-alive and keep waiting.
                 yield QueryKeepAliveModel().model_dump_json()
             else:
                 # The next value from the iterator is ready to read.
+                print("ready")
                 ready = True
     finally:
         # Even if we get cancelled above, we need to wait for this iteration to