Files
hermes-webui/tests/test_issue_1584_multitab_sse.py
T
nesquena-hermesandnesquena-hermes 9738ebb614 fix(tests): sync on subscriber count in multitab SSE test (#5628) (#5660)
test_same_stream_in_two_tabs_receives_identical_token_sequence started both
SSE-handler threads then immediately put_nowait'd the tokens + stream_end
without waiting for both threads to subscribe. StreamChannel.put_nowait()
buffers events only while there are zero subscribers and clears that buffer
the moment the first subscriber attaches and broadcasts live — so producing
events in the window after tab A subscribes but before tab B does orphans
tab B (subscribes to a cleared buffer, never sees stream_end, hangs ->
thread.join timeout -> 'every tab should finish' fails). ~20% timing flake
on slow CI runners (3.11 shard-4).

Wait until len(stream._subscribers) == len(handlers) (bounded 5s) before
producing events, so delivery is deterministic regardless of thread-start
timing. Test-only; no production change (buffer-then-broadcast is correct for
the real reconnect case).

Verified: original flakes 2/30 under CPU contention; fixed 30/30.

Fixes #5628

Co-authored-by: nesquena-hermes <nesquena-hermes@users.noreply.github.com>
2026-07-05 19:52:16 -07:00

107 lines
3.6 KiB
Python

import io
import threading
import time
from types import SimpleNamespace
from api.config import STREAMS, STREAMS_LOCK, create_stream_channel
from api.routes import _handle_sse_stream
class _FakeHandler:
def __init__(self):
self.status = None
self.headers = []
self.wfile = io.BytesIO()
def send_response(self, status):
self.status = status
def send_header(self, key, value):
self.headers.append((key, value))
def end_headers(self):
return None
def test_stream_channel_broadcasts_each_event_to_every_subscriber():
stream = create_stream_channel()
q1 = stream.subscribe()
q2 = stream.subscribe()
try:
stream.put_nowait(("token", {"text": "H"}))
stream.put_nowait(("token", {"text": "allo"}))
stream.put_nowait(("stream_end", {"status": "done"}))
assert q1.get(timeout=1) == ("token", {"text": "H"})
assert q1.get(timeout=1) == ("token", {"text": "allo"})
assert q1.get(timeout=1) == ("stream_end", {"status": "done"})
assert q2.get(timeout=1) == ("token", {"text": "H"})
assert q2.get(timeout=1) == ("token", {"text": "allo"})
assert q2.get(timeout=1) == ("stream_end", {"status": "done"})
finally:
stream.unsubscribe(q1)
stream.unsubscribe(q2)
def test_same_stream_in_two_tabs_receives_identical_token_sequence():
stream_id = "multitab-stream"
stream = create_stream_channel()
with STREAMS_LOCK:
STREAMS[stream_id] = stream
handlers = [_FakeHandler(), _FakeHandler()]
threads = [
threading.Thread(
target=_handle_sse_stream,
args=(handler, SimpleNamespace(query=f"stream_id={stream_id}")),
daemon=True,
)
for handler in handlers
]
try:
for thread in threads:
thread.start()
# Wait until BOTH tabs have actually subscribed before producing any
# events. StreamChannel.put_nowait() buffers events in _offline_buffer
# only while there are ZERO subscribers, and clears that buffer the
# moment the first subscriber attaches and it broadcasts live. If we
# put tokens in the window after tab A subscribes but before tab B
# does, tab B subscribes to an already-cleared buffer, never receives
# stream_end, and hangs -> thread.join times out (the ~20% timing flake
# on slow CI runners, issue #5628). Synchronize on the real subscriber
# count so the test is deterministic regardless of thread-start timing.
deadline = time.monotonic() + 5.0
subscribed = 0
while time.monotonic() < deadline:
with stream._lock:
subscribed = len(stream._subscribers)
if subscribed >= len(handlers):
break
time.sleep(0.005)
else:
raise AssertionError(
f"only {subscribed}/{len(handlers)} tabs subscribed before timeout"
)
stream.put_nowait(("token", {"text": "H"}))
stream.put_nowait(("token", {"text": "allo"}))
stream.put_nowait(("stream_end", {"status": "done"}))
for thread in threads:
thread.join(timeout=1)
assert not thread.is_alive(), "every tab should finish the same SSE stream"
for handler in handlers:
payload = handler.wfile.getvalue().decode("utf-8")
assert handler.status == 200
assert '"text": "H"' in payload
assert '"text": "allo"' in payload
assert "event: stream_end" in payload
finally:
with STREAMS_LOCK:
STREAMS.pop(stream_id, None)