added a config parameter to limit outbound p2p connections.

sei-tendermint/config/config.go

@@ -647,9 +647,13 @@ type P2PConfig struct {
 	// UPNP port forwarding. UNUSED
 	UPNP bool `mapstructure:"upnp"`
 
-	// MaxConnections defines the maximum number of connected peers (inbound and
-	// outbound).
-	MaxConnections uint16 `mapstructure:"max-connections"`
+	// MaxConnections limits the number of connected peers (inbound and outbound).
+	MaxConnections uint `mapstructure:"max-connections"`
+
+	// MaxOutboundConnections limits the number of outbound connections to regular (non-persistent) peers.
+	// It should be significantly lower than MaxConnections, unless
+	// the node is supposed to have a small number of connections altogether.
+	MaxOutboundConnections uint
 
 	// MaxIncomingConnectionAttempts rate limits the number of incoming connection
 	// attempts per IP address.
@@ -693,17 +697,21 @@ type P2PConfig struct {
 	// with the default being "priority".
 	QueueType string `mapstructure:"queue-type"`
 
-	// List of node IDs, to which a connection will be (re)established, dropping an existing peer if any existing limit has been reached
+	// List of node IDs, from which a connection will be accepted regardless of the connection limits.
 	UnconditionalPeerIDs string `mapstructure:"unconditional-peer-ids"`
 }
 
 // DefaultP2PConfig returns a default configuration for the peer-to-peer layer
 func DefaultP2PConfig() *P2PConfig {
 	return &P2PConfig{
-		ListenAddress:                 "tcp://127.0.0.1:26656",
-		ExternalAddress:               "",
-		UPNP:                          false,
-		MaxConnections:                100,
+		ListenAddress:   "tcp://127.0.0.1:26656",
+		ExternalAddress: "",
+		UPNP:            false,
+		MaxConnections:  100,
+		// TODO(gprusak): decrease to 10, once PEX is improved to:
+		// * exchange both inbound and outbound connections information
+		// * exchange information on handshake as well.
+		MaxOutboundConnections:        100,
 		MaxIncomingConnectionAttempts: 100,
 		FlushThrottleTimeout:          100 * time.Millisecond,
 		MaxPacketMsgPayloadSize:       1000000,