tcp: limit the number of connections in tcp suite test on non-linux hosts (#1507)

* Only run the 50 connection test on linux

* Only one stress test on linux instead of both

p2p/transport/testsuite/stream_suite.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"runtime"
 	"strconv"
 	"sync"
 	"testing"
@@ -417,9 +418,15 @@ func SubtestStress1Conn100Stream100Msg(t *testing.T, ta, tb transport.Transport,
 	})
 }
 
-func SubtestStress50Conn10Stream50Msg(t *testing.T, ta, tb transport.Transport, maddr ma.Multiaddr, peerA peer.ID) {
+func SubtestStressManyConn10Stream50Msg(t *testing.T, ta, tb transport.Transport, maddr ma.Multiaddr, peerA peer.ID) {
+	connNum := 5
+	if runtime.GOOS == "linux" {
+		// Linux can handle a higher number of conns here than other platforms in CI.
+		// See https://github.com/libp2p/go-libp2p/issues/1498.
+		connNum = 50
+	}
 	SubtestStress(t, ta, tb, maddr, peerA, Options{
-		ConnNum:   50,
+		ConnNum:   connNum,
 		StreamNum: 10,
 		MsgNum:    50,
 		MsgMax:    100,

p2p/transport/testsuite/utils_suite.go

@@ -21,7 +21,7 @@ var Subtests = []func(t *testing.T, ta, tb transport.Transport, maddr ma.Multiad
 	SubtestStress1Conn1Stream1Msg,
 	SubtestStress1Conn1Stream100Msg,
 	SubtestStress1Conn100Stream100Msg,
-	SubtestStress50Conn10Stream50Msg,
+	SubtestStressManyConn10Stream50Msg,
 	SubtestStress1Conn1000Stream10Msg,
 	SubtestStress1Conn100Stream100Msg10MB,
 	SubtestStreamOpenStress,
@@ -37,6 +37,7 @@ func SubtestTransport(t *testing.T, ta, tb transport.Transport, addr string, pee
 	if err != nil {
 		t.Fatal(err)
 	}
+
 	for _, f := range Subtests {
 		t.Run(getFunctionName(f), func(t *testing.T) {
 			f(t, ta, tb, maddr, peerA)