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perf: clean up SSE session writer #518

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perf: clean up SSE session writer #518

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f3ec291
perf: clean up SSE session writer
LeeEirc Apr 15, 2025
5f35e18
perf: use walrus and python lint
LeeEirc Apr 15, 2025
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17 changes: 16 additions & 1 deletion src/mcp/server/sse.py
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@ async def handle_sse(request):
from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
from pydantic import ValidationError
from sse_starlette import EventSourceResponse
from starlette.background import BackgroundTask
from starlette.requests import Request
from starlette.responses import Response
from starlette.types import Receive, Scope, Send
Expand Down Expand Up @@ -78,6 +79,17 @@ def __init__(self, endpoint: str) -> None:
self._read_stream_writers = {}
logger.debug(f"SseServerTransport initialized with endpoint: {endpoint}")

async def _remove_stream_writer(self, session_id: UUID) -> None:
"""
Remove the SSE session with the given session ID.
"""
logger.debug(f"Remove SSE session with ID: {session_id}")
if writer := self._read_stream_writers.pop(session_id, None):
await writer.aclose()
logger.debug(f"Closed SSE session with ID: {session_id}")
else:
logger.warning(f"Session ID {session_id} not found for removal")

@asynccontextmanager
async def connect_sse(self, scope: Scope, receive: Receive, send: Send):
if scope["type"] != "http":
Expand Down Expand Up @@ -120,9 +132,12 @@ async def sse_writer():
}
)

background_task = BackgroundTask(self._remove_stream_writer, session_id)
async with anyio.create_task_group() as tg:
response = EventSourceResponse(
content=sse_stream_reader, data_sender_callable=sse_writer
content=sse_stream_reader,
data_sender_callable=sse_writer,
background=background_task,
)
logger.debug("Starting SSE response task")
tg.start_soon(response, scope, receive, send)
Expand Down