diff --git a/litellm/proxy/proxy_server.py b/litellm/proxy/proxy_server.py index e1005b9a758..f8902f6276a 100644 --- a/litellm/proxy/proxy_server.py +++ b/litellm/proxy/proxy_server.py @@ -10012,6 +10012,7 @@ def _pop_complete_sse_frame(buffer: str) -> tuple[str | None, str]: _STREAM_KEEPALIVE: Final = object() _KEEPALIVE_MIN_SECONDS: Final = 1.0 +_STREAM_LOOP_HOLD_SECONDS: Final = 0.05 _KEEPALIVE_MAX_SECONDS: Final = 300.0 _EMPTY_MAPPING: Final[Mapping[str, object]] = MappingProxyType({}) _EMPTY_HEADERS: Final[Mapping[str, str]] = MappingProxyType({}) @@ -10287,10 +10288,13 @@ async def async_data_generator( else stream_iterator ) + loop_released_at = time.monotonic() # rebind-ok: last time this stream let other tasks run async for item in stream_source: # Unblock the event loop: a stream whose chunks are already buffered never awaits # between chunks, so without this yield one long stream holds the loop for its whole body - await asyncio.sleep(0) + if time.monotonic() - loop_released_at >= _STREAM_LOOP_HOLD_SECONDS: + await asyncio.sleep(0) + loop_released_at = time.monotonic() if item is _STREAM_KEEPALIVE: yield ": ping\n\n" continue diff --git a/tests/unit/proxy/proxy_server/test_streaming_helpers.py b/tests/unit/proxy/proxy_server/test_streaming_helpers.py index 930c7004449..f53e1931782 100644 --- a/tests/unit/proxy/proxy_server/test_streaming_helpers.py +++ b/tests/unit/proxy/proxy_server/test_streaming_helpers.py @@ -2095,13 +2095,17 @@ def test_fast_serialize_simple_model_response_stream_keeps_served_service_tier() @pytest.mark.asyncio async def test_async_data_generator_lets_other_tasks_run_during_a_stream_that_never_waits(monkeypatch): """A stream whose chunks are already buffered never suspends on its own, so - the generator has to hand the loop back itself: another task must get to - run before the stream is over.""" + the generator has to hand the loop back itself once it has held the loop + long enough: another task must get to run before the stream is over, and + not before the hold budget is used up.""" _patch_logging_flags(monkeypatch) order: list[str] = [] # mutable-ok: records the interleaving of the two tasks + clock: list[float] = [0.0] # mutable-ok: fake monotonic clock, advanced 20 ms per chunk + monkeypatch.setattr(ps.time, "monotonic", lambda: clock[0]) async def chunks(): for index in range(6): + clock[0] += 0.02 order.append(f"chunk{index}") yield _simple_chunk(content=str(index)) @@ -2118,3 +2122,4 @@ async def test_async_data_generator_lets_other_tasks_run_during_a_stream_that_ne await other assert "other" in order[:-1], order + assert order.index("other") >= 3, order