fix: eliminate port race in setupFakeEnvoyStats test helper - #9580
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net.Listen(":0") followed by l.Close() and a later ListenAndServe() on
the resulting port number leaves a window where another process (or a
concurrently running test) can grab that exact ephemeral port before
the re-bind happens, causing TestGetTotalConnections to fail with
connection errors on loaded machines. Serve on the already-bound
listener directly via s.Serve(l) so the port is never released.
Signed-off-by: Muhammad Waqar <mwaqar@confluent.io>
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #9580 +/- ##
==========================================
- Coverage 75.64% 75.59% -0.05%
==========================================
Files 252 252
Lines 41758 41758
==========================================
- Hits 31589 31569 -20
- Misses 8046 8062 +16
- Partials 2123 2127 +4 ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
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arkodg
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Jul 26, 2026
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Summary
setupFakeEnvoyStatsininternal/cmd/envoy/shutdown_manager_test.gobinds an ephemeral port withnet.Listen(":0"), immediately closes that listener, and later re-binds to the same port number vias.ListenAndServe(). This is a classic time-of-check-to-time-of-use race: betweenl.Close()and the goroutine'sListenAndServe()actually completing its bind, another process (or a concurrently running test) can grab that exact port number, causingTestGetTotalConnectionsto fail intermittently on loaded machines with errors likeerror getting listener downstream_cx_active stat: Get ..., while the real cause (fail to listen: ...) is only printed to stdout rather than failing the test directly.Fix
Keep the original
net.Listenerand calls.Serve(l)instead ofs.ListenAndServe(), so the already-bound listener is reused and the port is never released and re-acquired.Test plan
go build ./...go test -race -run TestGetTotalConnections -count=200 ./internal/cmd/envoy/...— clean