[PR #9407/e653b281 backport][3.11] Add __slots__ to stream classes

CHANGES/9407.misc.rst

@@ -0,0 +1 @@
+Reduced memory required for stream objects created during the client request lifecycle -- by :user:`bdraco`.

aiohttp/streams.py

@@ -39,6 +39,9 @@ class EofStream(Exception):
 
 
 class AsyncStreamIterator(Generic[_T]):
+
+    __slots__ = ("read_func",)
+
     def __init__(self, read_func: Callable[[], Awaitable[_T]]) -> None:
         self.read_func = read_func
 
@@ -56,6 +59,9 @@ async def __anext__(self) -> _T:
 
 
 class ChunkTupleAsyncStreamIterator:
+
+    __slots__ = ("_stream",)
+
     def __init__(self, stream: "StreamReader") -> None:
         self._stream = stream
 
@@ -70,6 +76,9 @@ async def __anext__(self) -> Tuple[bytes, bool]:
 
 
 class AsyncStreamReaderMixin:
+
+    __slots__ = ()
+
     def __aiter__(self) -> AsyncStreamIterator[bytes]:
         return AsyncStreamIterator(self.readline)  # type: ignore[attr-defined]
 
@@ -104,7 +113,25 @@ class StreamReader(AsyncStreamReaderMixin):
 
     """
 
-    total_bytes = 0
+    __slots__ = (
+        "_protocol",
+        "_low_water",
+        "_high_water",
+        "_loop",
+        "_size",
+        "_cursor",
+        "_http_chunk_splits",
+        "_buffer",
+        "_buffer_offset",
+        "_eof",
+        "_waiter",
+        "_eof_waiter",
+        "_exception",
+        "_timer",
+        "_eof_callbacks",
+        "_eof_counter",
+        "total_bytes",
+    )
 
     def __init__(
         self,
@@ -131,6 +158,8 @@ def __init__(
         self._exception: Optional[BaseException] = None
         self._timer = TimerNoop() if timer is None else timer
         self._eof_callbacks: List[Callable[[], None]] = []
+        self._eof_counter = 0
+        self.total_bytes = 0
 
     def __repr__(self) -> str:
         info = [self.__class__.__name__]
@@ -517,6 +546,9 @@ def _read_nowait(self, n: int) -> bytes:
 
 
 class EmptyStreamReader(StreamReader):  # lgtm [py/missing-call-to-init]
+
+    __slots__ = ("_read_eof_chunk",)
+
     def __init__(self) -> None:
         self._read_eof_chunk = False
 

tests/test_flowcontrol_streams.py

@@ -12,16 +12,12 @@ def protocol():
 
 @pytest.fixture
 def stream(loop, protocol):
-    out = streams.StreamReader(protocol, limit=1, loop=loop)
-    out._allow_pause = True
-    return out
+    return streams.StreamReader(protocol, limit=1, loop=loop)
 
 
 @pytest.fixture
 def buffer(loop, protocol):
-    out = streams.FlowControlDataQueue(protocol, limit=1, loop=loop)
-    out._allow_pause = True
-    return out
+    return streams.FlowControlDataQueue(protocol, limit=1, loop=loop)
 
 
 class TestFlowControlStreamReader: