fix after test on 4 nodes

server/concurrent/async_local_client.go

@@ -425,22 +425,37 @@ func (app *asyncLocalClient) EndBlockSync(req types.RequestEndBlock) (*types.Res
 //-------------------------------------------------------
 
 func (app *asyncLocalClient) LatestSnapshot() (height int64, numKeys []int64, err error) {
+	app.rwLock.RLock()
+	defer app.rwLock.RUnlock()
+
 	return app.Application.LatestSnapshot()
 }
 
 func (app *asyncLocalClient) ReadSnapshotChunk(height int64, startIndex, endIndex int64) (chunk [][]byte, err error) {
+	app.rwLock.RLock()
+	defer app.rwLock.RUnlock()
+
 	return app.Application.ReadSnapshotChunk(height, startIndex, endIndex)
 }
 
 func (app *asyncLocalClient) StartRecovery(height int64, numKeys []int64) error {
+	app.rwLock.Lock()
+	defer app.rwLock.Unlock()
+
 	return app.Application.StartRecovery(height, numKeys)
 }
 
 func (app *asyncLocalClient) WriteRecoveryChunk(chunk [][]byte) error {
+	app.rwLock.Lock()
+	defer app.rwLock.Unlock()
+
 	return app.Application.WriteRecoveryChunk(chunk)
 }
 
 func (app *asyncLocalClient) EndRecovery(height int64) error {
+	app.rwLock.Lock()
+	defer app.rwLock.Unlock()
+
 	return app.Application.EndRecovery(height)
 }