Aias00 opened a new issue, #3544:
URL: https://github.com/apache/dubbo-go/issues/3544
### Problem
`registry/etcdv3.dataListener.interestedURL` is a plain `[]*common.URL`
slice with no lock:
```go
// registry/etcdv3/listener.go
type dataListener struct {
interestedURL []*common.URL
listener config_center.ConfigurationListener
}
func (l *dataListener) AddInterestedURL(url *common.URL) {
l.interestedURL = append(l.interestedURL, url) // DoSubscribe path
}
func (l *dataListener) DataChange(eventType remoting.Event) bool {
...
if slices.ContainsFunc(l.interestedURL, serviceURL.URLEqual) { // etcd
watch goroutine
l.listener.Process(...)
}
}
```
`AddInterestedURL` is called from `DoSubscribe` (consumer subscribe path)
while `DataChange` runs on the etcd watch goroutine (`ListenServiceEvent`).
Concurrent `append` (which may reallocate the slice header) and
`slices.ContainsFunc` (which reads the slice header/elements) is a data race.
`go test -race` flags it.
### Current behavior
Two near-simultaneous `DoSubscribe` calls, or a subscribe concurrent with an
incoming etcd watch event, race on the `interestedURL` slice header → torn
reads, missed event matching, or stale reads dropping events.
### Expected behavior
`interestedURL` reads and writes must be guarded; `DataChange` must not hold
the lock across the external `Process` callback.
### Suggested approach
- Add a `sync.RWMutex` to `dataListener`.
- `AddInterestedURL` takes the write lock.
- `DataChange` does the `slices.ContainsFunc` check under `RLock`, releases
it, then dispatches `Process` outside the lock.
### Acceptance criteria
- [ ] `interestedURL` is accessed under the mutex in both `AddInterestedURL`
and `DataChange`.
- [ ] `DataChange` dispatches `Process` outside the lock.
- [ ] A concurrency test (concurrent `AddInterestedURL` vs `DataChange`)
passes under `-race`.
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