recreate peer selector in fetchRound

catchup/service.go

@@ -738,7 +738,15 @@ func (s *Service) fetchRound(cert agreement.Certificate, verifier *agreement.Asy
 				// None, there is no exit condition on too many retries as per the function contract.
 				if count, ok := peerErrors[peer]; ok {
 					if count > errNoBlockForRoundThreshold {
-						time.Sleep(100 * time.Millisecond)
+						time.Sleep(50 * time.Millisecond)
+					}
+					if count > errNoBlockForRoundThreshold*10 {
+						// for the low number of connected peers (like 2) the following scenatio is possible:
+						// - both peers do not have the block
+						// - peer selector punishes one of the peers more than the other
+						// - the punoshed peer gets the block, and the less punished peer stucks.
+						// It this case reset the peer selector to let it re-learn priorities.
+						peerSelector = createPeerSelector(s.net, s.cfg, false)
 					}
 				}
 				peerErrors[peer]++

catchup/service_test.go

@@ -495,8 +495,6 @@ func TestServiceFetchBlocksMultiBlocks(t *testing.T) {
 	}
 	addBlocks(t, remote, blk, int(numberOfBlocks)-1)
 
-	logging.Base().SetLevel(logging.Debug)
-
 	// Create a network and block service
 	blockServiceConfig := config.GetDefaultLocal()
 	net := &httpTestPeerSource{}
@@ -531,7 +529,6 @@ func TestServiceFetchBlocksMultiBlocks(t *testing.T) {
 		localBlock, err := local.Block(i)
 		require.NoError(t, err)
 		require.Equal(t, *blk, localBlock)
-		return
 	}
 }