test: shave ServiceBrowser first-query delay on loopback#1720
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bdraco merged 1 commit intoMay 18, 2026
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`ServiceBrowser` waits `random.randint(20, 120)` ms before its first query — RFC 6762 §5.2 thundering-herd avoidance for real networks, pure overhead on 127.0.0.1. Every browser-using test pays it, and `ZeroconfServiceTypes.find()` adds it on top of `time.sleep(timeout)` because find() doesn't short-circuit on the first response. Extend `quick_timing` to also patch `_FIRST_QUERY_DELAY_RANDOM_INTERVAL` to (1, 5) ms, drop `LOOPBACK_FIND_TIMEOUT` from 200 → 75 ms (still ~7x headroom over the ~10 ms response latency on loopback), and apply `quick_timing` to the four `test_integration_with_*` tests in tests/services/test_types.py. Numbers on a local run: test_integration_with_listener 0.67s → 0.20s test_integration_with_listener_v6_records 0.69s → 0.19s test_integration_with_subtype_and_listener 0.68s → 0.19s test_integration_with_listener_ipv6 0.69s → 0.20s test_async_zeroconf_service_types 0.74s → 0.55s Full suite: 48.78s → 42.94s (-12%). Part of python-zeroconf#1707.
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bdraco
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May 18, 2026
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What
Extend the
quick_timingtest fixture to also shrinkServiceBrowser's first-query delay from RFC 6762 §5.2's 20–120 mswindow to 1–5 ms on loopback, drop
LOOPBACK_FIND_TIMEOUTfrom200 → 75 ms, and apply
quick_timingto the fourtest_integration_with_*tests intests/services/test_types.py.Part of #1707.
Why
ServiceBrowser.__init__schedules its first query atrandom.randint(20, 120)ms — thundering-herd avoidance for realnetworks, pure overhead on 127.0.0.1. Every browser-using test pays
it, and
ZeroconfServiceTypes.find()adds it on top oftime.sleep(timeout)becausefind()doesn't short-circuit onthe first matching response — so
timeoutis a lower bound onruntime and the in-browser jitter has to fit underneath it.
The four
test_types.pyintegration tests each callfind()twicewith
LOOPBACK_FIND_TIMEOUT = 0.2 s, so they pay 400 ms of deadwait alone. With first-query delay at ≤5 ms the response lands
inside ~10 ms; 75 ms leaves ~7× headroom while halving the floor.
How
tests/conftest.py: extendquick_timingto alsopatch.object(service_browser, "_FIRST_QUERY_DELAY_RANDOM_INTERVAL", (1, 5)).The constant is read once at
ServiceBrowser.__init__-time andpassed to
QueryScheduler— patching the module attribute beforeany browser is constructed is sufficient.
tests/__init__.py: dropLOOPBACK_FIND_TIMEOUTto0.075andupdate the comment to note callers MUST use
quick_timing.tests/services/test_types.py: addquick_timingto all fourintegration tests (they do not register via probing so the
_CHECK_TIME/_REGISTER_TIMEshaves are no-ops, but thebrowser-delay shave is real).
Testing
poetry run pytest --durations=20 --timeout=60 -q tests— 339 passed, 2 skipped.Slowest-tests deltas (local, single run):
test_integration_with_listenertest_integration_with_listener_v6_recordstest_integration_with_subtype_and_listenertest_integration_with_listener_ipv6test_async_zeroconf_service_typesFull suite: 48.78 s → 42.94 s (-12%).
Quality Report
Changes: 3 files changed, 18 insertions(+), 12 deletions(-)
Code scan: clean
Tests: passed (4 PASSED)
Branch hygiene: clean
Generated by Kōan post-mission quality pipeline