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test(storage): fix flaky minimemcached nil-pointer panic #4301

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test(storage): fix flaky minimemcached nil-pointer panic #4301

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f1a0942
test(storage): fix flaky minimemcached nil-pointer panic
reinkrul Jun 2, 2026
86636a3
test(storage): link upstream issue for the minimemcached workaround
reinkrul Jun 2, 2026
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24 changes: 20 additions & 4 deletions storage/session_memcached_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -170,11 +170,27 @@ func memcachedTestServer(t *testing.T) *minimemcached.MiniMemcached {
if err != nil {
t.Fatal(err)
}
// Workaround for https://github.com/daangn/minimemcached/issues/14 (fix proposed in PR #13).
// Wait until the server's accept loop is actually serving connections before returning.
// minimemcached.Run spawns a goroutine that calls Accept() on the listener; Close() nils that
// listener. On really short tests Close() (in the cleanup below) could run before the goroutine
// entered Accept(), causing a nil pointer dereference in the dependency. Probing the server until
// it answers guarantees the accept loop is parked in Accept(), so Close() unblocks it cleanly.
// Remove this workaround once a minimemcached release includes the upstream fix.
require.Eventually(t, func() bool {
conn, err := net.DialTimeout("tcp", fmt.Sprintf("localhost:%d", m.Port()), time.Second)
if err != nil {
return false
}
defer conn.Close()
if _, err = conn.Write([]byte("version\r\n")); err != nil {
return false
}
buf := make([]byte, 1)
_, err = conn.Read(buf)
return err == nil
}, 5*time.Second, 10*time.Millisecond, "memcached server did not start serving")
t.Cleanup(func() {
// Note on DATA RACE
// minimemcached.Run creates a new go routine to listen for new connections.
// In certain cases the new go routine may be created after/simultaneous with this cleanup resulting in a data race / nil pointer dereference.
// Mostly happens on CI during really short tests.
m.Close()
})
return m
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