[sync] changed param to support low network bandwidth against large b…

…lock (#3766)

* [sync] changed param to support low network bandwidth against large block

* [sync] increase the retry limit per process loop

api/service/legacysync/downloader/client.go

@@ -93,7 +93,7 @@ func (client *Client) GetBlocks(hashes [][]byte) *pb.DownloaderResponse {
 
 // GetBlocksAndSigs get blockWithSig in serialization byte array by calling a grpc request
 func (client *Client) GetBlocksAndSigs(hashes [][]byte) *pb.DownloaderResponse {
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), 300*time.Second)
 	defer cancel()
 	request := &pb.DownloaderRequest{Type: pb.DownloaderRequest_BLOCK, GetBlocksWithSig: true}
 	request.Hashes = make([][]byte, len(hashes))

api/service/legacysync/syncing.go

@@ -29,20 +29,20 @@ import (
 
 // Constants for syncing.
 const (
-	downloadBlocksRetryLimit        = 5 // downloadBlocks service retry limit
+	downloadBlocksRetryLimit        = 10 // downloadBlocks service retry limit
 	RegistrationNumber              = 3
 	SyncingPortDifference           = 3000
-	inSyncThreshold                 = 0    // when peerBlockHeight - myBlockHeight <= inSyncThreshold, it's ready to join consensus
-	SyncLoopBatchSize        uint32 = 1000 // maximum size for one query of block hashes
-	verifyHeaderBatchSize    uint64 = 100  // block chain header verification batch size
+	inSyncThreshold                 = 0   // when peerBlockHeight - myBlockHeight <= inSyncThreshold, it's ready to join consensus
+	SyncLoopBatchSize        uint32 = 30  // maximum size for one query of block hashes
+	verifyHeaderBatchSize    uint64 = 100 // block chain header verification batch size (not used for now)
 	LastMileBlocksSize              = 50
 
 	// after cutting off a number of connected peers, the result number of peers
 	// shall be between numPeersLowBound and numPeersHighBound
 	NumPeersLowBound  = 3
 	numPeersHighBound = 5
 
-	downloadTaskBatch = 15
+	downloadTaskBatch = 5
 )
 
 // SyncPeerConfig is peer config to sync.