Merge pull request #3519 from zsfelfoldi/light-topic5

les: fixed selectPeer deadlock, improved request distribution

les/peer.go

@@ -241,7 +241,9 @@ func (p *peer) RequestHeaderProofs(reqID, cost uint64, reqs []*ChtReq) error {
 
 func (p *peer) SendTxs(cost uint64, txs types.Transactions) error {
 	glog.V(logger.Debug).Infof("%v relaying %v txs", p, len(txs))
-	p.fcServer.SendRequest(0, cost)
+	reqID := getNextReqID()
+	p.fcServer.MustAssignRequest(reqID)
+	p.fcServer.SendRequest(reqID, cost)
 	return p2p.Send(p.rw, SendTxMsg, txs)
 }