go test -race ./internal/gateway failed in TestQuietStreamsKeptAliveEveryProtocol
(chat held) with six data races: keepAlive, on watch's goroutine, sent the
held stream's 200 with the try's headers by iterating holdWriter.header,
while the try's goroutine wrote that map with no lock: noteMember (#822's
X-Magpie-Provider/Model) and passthrough copying the vendor's headers in.
In production, a vendor that answers only after keepHeldAfter does the
same, and outside -race that can end the process with "concurrent map
iteration and map write".
Before the try has its status (WriteHeader, under mu), keepAlive now sends
only magpie's own notes, which noteMember sets under mu (holdWriter.note);
the vendor has said nothing yet, so nothing of its is lost. It also clones
what it copies, so the agent's header shares no slice with the try's.
TestKeepAliveBeforeTheVendorsHeaders (a try writing its headers while the
first comment goes out) reports the race on the old code (2 of 3 runs);
-race -count=20 passes, and so does the whole package under -race.
yetone
443f1cbc2d