PR #468 shipped without a codex review because codex was unavailable
that day. This is the catch-up; codex found 2 P2s and 5 NITs.
[P2] readSendTimestamp recorded latencies for prior-run replay
frames. The original guard only checked nonzero ts, not session
recency, so any stale op-log row inflated p95/p99. Fixed: runContext
captures startedAt; recv path filters frames whose embedded ts
predates this run. Verified: against an item with 90 stale rows the
test counts received frames (630) but only records latencies for
the 180 live ones.
[P2] Shutdown deadlock. The writer goroutine could be blocked in
conn.WriteMessage when rc.done closed; the only path to conn.Close
was that same goroutine's select-case, so wg.Wait() could hang
forever under server backpressure. Fixed: per-client watchdog
goroutine closes the conn from outside the writer when done fires,
plus a 5s SetWriteDeadline per send as defence-in-depth. A 5s
duration test now exits in exactly 5.008s.
NITs (also fixed):
- buildFrame docstring corrected (minimum is 16 metadata bytes,
buffer is frameBytes+1).
- buildFrame returns (bytes, error) instead of log.Fatalf-ing on
rand.Read; caller logs detail and increments errors counter.
- -cookie / -token flag help now states both can be set together.
- Watchdog-induced WriteMessage errors are no longer counted as
real errors (isClosedDone check).
- buildFrame error path now logs the actual error detail.
Two rounds of codex review: round 1 found the items above; round 2
returned CLEAN.
Synthetic Go load-test for the Yjs collab dumb-relay. Each
simulated client opens a WebSocket, sends tagged sync frames at
a configurable rate, consumes inbound frames, and computes
broadcast fanout latency.
Doesn't depend on a real Yjs port — the dumb-relay's first-byte
discriminator (yMessageSync=0) is enough to exercise the persist +
broadcast path with synthetic payloads. Each frame embeds a
unix-nano timestamp + client ID so receivers can compute round-
trip latency without out-of-band coordination.
Findings (in DOC-1307):
- N=5, N=25: clean, p95 < 10ms, fanout matches expected (N-1)x
- N=100: 38/100 dial failures (consistent), but the 62 successful
see p95=27ms — server rejects ~38% of simultaneous dials at this
level. Filed BUG-1308 to investigate the ceiling.
- Op-log grows unbounded without compaction; old runs replay
on reconnect causing latency blow-up. Filed TASK-1309 to wire
a periodic prune sweeper.
Self-reviewed only; codex was unresponsive today after multiple
hour-long retries.
xarmian