Reduce startup memory for gateways

Similar to #956 but for gateways code.
Also fixing route test TestLargeClusterMem.

Signed-off-by: Ivan Kozlovic <ivan@synadia.com>

server/gateway.go

@@ -673,7 +673,7 @@ func (s *Server) createGateway(cfg *gatewayCfg, url *url.URL, conn net.Conn) {
 	}
 
 	// Do final client initialization
-	c.in.pacache = make(map[string]*perAccountCache, maxPerAccountCacheSize)
+	c.in.pacache = make(map[string]*perAccountCache)
 	if solicit {
 		// This is an outbound gateway connection
 		c.gw.outsim = &sync.Map{}

server/gateway_test.go

@@ -4433,3 +4433,47 @@ func TestGatewayServiceExportWithWildcards(t *testing.T) {
 		})
 	}
 }
+
+func TestGatewayMemUsage(t *testing.T) {
+	// Try to clean up.
+	runtime.GC()
+	var m runtime.MemStats
+	runtime.ReadMemStats(&m)
+	pta := m.TotalAlloc
+
+	o := testDefaultOptionsForGateway("A")
+	s := runGatewayServer(o)
+	defer s.Shutdown()
+
+	var servers []*Server
+	servers = append(servers, s)
+
+	numServers := 10
+	for i := 0; i < numServers; i++ {
+		rn := fmt.Sprintf("RG_%d", i+1)
+		o := testGatewayOptionsFromToWithServers(t, rn, "A", s)
+		s := runGatewayServer(o)
+		defer s.Shutdown()
+		servers = append(servers, s)
+	}
+
+	// Each server should have an outbound
+	for _, s := range servers {
+		waitForOutboundGateways(t, s, numServers, 2*time.Second)
+	}
+	// The first started server should have numServers inbounds (since
+	// they all connect to it).
+	waitForInboundGateways(t, s, numServers, 2*time.Second)
+
+	// Calculate in MB what we are using now.
+	const max = 50 * 1024 * 1024 // 50MB
+	runtime.ReadMemStats(&m)
+	used := m.TotalAlloc - pta
+	if used > max {
+		t.Fatalf("Cluster using too much memory, expect < 50MB, got %dMB", used/(1024*1024))
+	}
+
+	for _, s := range servers {
+		s.Shutdown()
+	}
+}

test/new_routes_test.go

@@ -1629,7 +1629,7 @@ func TestLargeClusterMem(t *testing.T) {
 	rurl, _ := url.Parse(routeAddr)
 	routes := []*url.URL{rurl}
 
-	numServers := 25
+	numServers := 15
 
 	for i := 1; i < numServers; i++ {
 		o := opts()
@@ -1642,9 +1642,9 @@ func TestLargeClusterMem(t *testing.T) {
 	// Calculate in MB what we are using now.
 	const max = 50 * 1024 * 1024 // 50MB
 	runtime.ReadMemStats(&m)
-	used := (m.TotalAlloc - pta) / (1024 * 1024)
+	used := m.TotalAlloc - pta
 	if used > max {
-		t.Fatalf("Cluster using too much memory, expect < 50MB, got %dMB", used)
+		t.Fatalf("Cluster using too much memory, expect < 50MB, got %dMB", used/(1024*1024))
 	}
 
 	for _, s := range servers {