Aias00 opened a new pull request, #3521:
URL: https://github.com/apache/dubbo-go/pull/3521
## What
`List` and `IsAvailable` read `dir.invokers` without a lock, while `Destroy`
reassigns it under `base.Directory.mutex` (via `DoDestroy`). The unlocked reads
race the write (data race on the slice header).
## Why
```go
// cluster/directory/static/directory.go
func (dir *directory) IsAvailable() bool {
...
if len(dir.invokers) == 0 { ... } // unlocked read
for _, invoker := range dir.invokers { ... } // unlocked range
}
func (dir *directory) List(...) []protocolbase.Invoker {
l := len(dir.invokers); ... copy(invokers, dir.invokers) // unlocked
read
}
func (dir *directory) Destroy() {
dir.DoDestroy(func() { ...; dir.invokers = []protocolbase.Invoker{} })
// write under base.Directory.mutex
}
```
`base.Directory.mutex` is unexported and not accessible from the `static`
package, so the static directory needs its own lock for `invokers`.
## Fix
Add a `sync.RWMutex` to the static `directory`:
- `IsAvailable`/`List` snapshot `invokers` under `RLock` and iterate the
snapshot.
- `List` releases the lock **before** calling `RouterChain()` (which takes
`base.Directory.mutex`) so the two locks never nest — no deadlock.
- `Destroy`'s closure writes `invokers` under the new lock (inside
`DoDestroy`, which holds `base.Directory.mutex`; no other path holds the new
lock while waiting for `base.Directory.mutex`).
## Tests
Added `TestStaticDirListVsDestroyRace`: 50 rounds of concurrent
`List`/`IsAvailable`/`Destroy`, passing under `-race`.
Fixes #3520
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