Claude
09631dcaab
Fixes found during self-correction before publishing: - /stream used Flux.interval(), which ticks on its own wall-clock schedule independent of downstream demand and threw OverflowException under a slow subscriber; switched to Flux.range(), which has no independent production schedule and can never outrun demand. - Single-trial HTTP load tests on this shared sandbox swung by more than 50% run to run (795ms-1247ms observed on the identical /io endpoint back to back) -- large enough to flip which threading model looked faster. Fixed by taking the median of 5 independent trials for the I/O-bound benchmark and the median of 3 for the event-loop-starvation benchmark, rather than reporting a single noisy run as if it were precise. - The event-loop-starvation test's first cut used only 8 concurrent /cpu requests as background load, which drained through the 4 event-loop threads well inside the /io measurement window and produced an inconsistent, sometimes-inverted result across runs; raising to 60 fixed the under-loading problem but still flaked once during verification (372ms vs 374ms p99, a real tie). Final fix: 150 concurrent requests plus the median-of-3 trials above. Also adds StreamBackpressureTest, a StepVerifier proof that the /stream endpoint never emits ahead of its subscriber's outstanding requests, and updates the module's docs to report the de-noised numbers with an explicit methodology note on how they compare to the single-trial platform/virtual- thread numbers reused from a different post.
14 lines
726 B
Plaintext
14 lines
726 B
Plaintext
Flux backpressure proof: /stream, requested in batches of 3, 2, then 45
|
|
=======================================================================
|
|
StepVerifier.create(controller.streamResults(), 3)
|
|
.expectNext("event-0", "event-1", "event-2")
|
|
.expectNoEvent(Duration.ofMillis(80)) -- no 4th item arrives without a request
|
|
.thenRequest(2).expectNext("event-3", "event-4")
|
|
.thenRequest(45).expectNextCount(45)
|
|
.expectComplete()
|
|
|
|
RESULT: verified -- the flux emitted exactly as many items as were requested, in
|
|
the order requested, with no items arriving ahead of a pending request. This is
|
|
what "backpressure is part of the Flux contract" means concretely: the subscriber,
|
|
not the producer, controls the emission rate.
|