Optimize slice memory allocations at different places: (istio#26550)

Avoid unwanted memory allocations by setting capacity for slices as length whenever length is known to create accurate size array to back it. It is already handled in many places in the code and missed in few. Hence, this commit fixes it. Signed-off-by: Aliasgar Ginwala <aginwala@ebay.com>
sel · Aug 24, 2020 · 8dfaf33 · 8dfaf33
1 parent ef21054
commit 8dfaf33
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Showing 14 changed files with 27 additions and 26 deletions.
diff --git a/istioctl/cmd/add-to-mesh.go b/istioctl/cmd/add-to-mesh.go
@@ -355,7 +355,6 @@ func injectSideCarIntoDeployment(client kubernetes.Interface, deps []appsv1.Depl
 }
 
 func findDeploymentsForSvc(client kubernetes.Interface, ns, name string) ([]appsv1.Deployment, error) {
-	deps := make([]appsv1.Deployment, 0)
 	svc, err := client.CoreV1().Services(ns).Get(context.TODO(), name, metav1.GetOptions{})
 	if err != nil {
 		return nil, err
@@ -368,6 +367,7 @@ func findDeploymentsForSvc(client kubernetes.Interface, ns, name string) ([]apps
 	if err != nil {
 		return nil, err
 	}
+	deps := make([]appsv1.Deployment, 0, len(deployments.Items))
 	for _, dep := range deployments.Items {
 		depLabels := k8s_labels.Set(dep.Spec.Selector.MatchLabels)
 		if svcSelector.Matches(depLabels) {
@@ -481,15 +481,15 @@ func generateServiceEntry(u *unstructured.Unstructured, o *vmServiceOpts) error
 	if o == nil {
 		return fmt.Errorf("empty vm service options")
 	}
-	ports := make([]*v1alpha3.Port, 0)
+	ports := make([]*v1alpha3.Port, 0, len(o.PortList))
 	for _, p := range o.PortList {
 		ports = append(ports, &v1alpha3.Port{
 			Number:   uint32(p.Port),
 			Protocol: string(p.Protocol),
 			Name:     p.Name,
 		})
 	}
-	eps := make([]*v1alpha3.WorkloadEntry, 0)
+	eps := make([]*v1alpha3.WorkloadEntry, 0, len(o.IP))
 	for _, ip := range o.IP {
 		eps = append(eps, &v1alpha3.WorkloadEntry{
 			Address: ip,
@@ -528,7 +528,7 @@ func resourceName(hostShortName string) string {
 }
 
 func generateK8sService(s *corev1.Service, o *vmServiceOpts) {
-	ports := make([]corev1.ServicePort, 0)
+	ports := make([]corev1.ServicePort, 0, len(o.PortList))
 	for _, p := range o.PortList {
 		ports = append(ports, corev1.ServicePort{
 			Name: strings.ToLower(p.Name),

diff --git a/istioctl/cmd/analyze.go b/istioctl/cmd/analyze.go
@@ -141,7 +141,7 @@ istioctl analyze -L
 				resource.Namespace(selectedNamespace), resource.Namespace(istioNamespace), nil, true, analysisTimeout)
 
 			// Check for suppressions and add them to our SourceAnalyzer
-			var suppressions []snapshotter.AnalysisSuppression
+			suppressions := make([]snapshotter.AnalysisSuppression, 0, len(suppress))
 			for _, s := range suppress {
 				parts := strings.Split(s, "=")
 				if len(parts) != 2 {

diff --git a/istioctl/cmd/convert_ingress.go b/istioctl/cmd/convert_ingress.go
@@ -76,7 +76,7 @@ func convertConfigs(readers []io.Reader, writer io.Writer, client kubernetes.Int
 }
 
 func readConfigs(readers []io.Reader) ([]model.Config, []*v1beta1.Ingress, error) {
-	out := make([]model.Config, 0)
+	out := make([]model.Config, 0, len(readers))
 	outIngresses := make([]*v1beta1.Ingress, 0)
 
 	for _, reader := range readers {

diff --git a/istioctl/cmd/describe.go b/istioctl/cmd/describe.go
@@ -112,7 +112,7 @@ THIS COMMAND IS STILL UNDER ACTIVE DEVELOPMENT AND NOT READY FOR PRODUCTION USE.
 				return err
 			}
 
-			matchingServices := []v1.Service{}
+			matchingServices := make([]v1.Service, 0, len(svcs.Items))
 			for _, svc := range svcs.Items {
 				if len(svc.Spec.Selector) > 0 {
 					svcSelector := k8s_labels.SelectorFromSet(svc.Spec.Selector)
@@ -220,8 +220,8 @@ func extendFQDN(host string) string {
 
 // getDestRuleSubsets gets names of subsets that match any pod labels (also, ones that don't match).
 func getDestRuleSubsets(subsets []*v1alpha3.Subset, podsLabels []k8s_labels.Set) ([]string, []string) {
-	matchingSubsets := []string{}
-	nonmatchingSubsets := []string{}
+	matchingSubsets := make([]string, 0, len(subsets))
+	nonmatchingSubsets := make([]string, 0, len(subsets))
 	for _, subset := range subsets {
 		subsetSelector := k8s_labels.SelectorFromSet(subset.Labels)
 		if matchesAnyPod(subsetSelector, podsLabels) {

diff --git a/istioctl/pkg/writer/envoy/configdump/cluster.go b/istioctl/pkg/writer/envoy/configdump/cluster.go
@@ -93,7 +93,7 @@ func (c *ConfigWriter) PrintClusterDump(filter ClusterFilter) error {
 	if err != nil {
 		return err
 	}
-	filteredClusters := protio.MessageSlice{}
+	filteredClusters := make(protio.MessageSlice, 0, len(clusters))
 	for _, cluster := range clusters {
 		if filter.Verify(cluster) {
 			filteredClusters = append(filteredClusters, cluster)

diff --git a/istioctl/pkg/writer/envoy/configdump/listener.go b/istioctl/pkg/writer/envoy/configdump/listener.go
@@ -110,7 +110,7 @@ func (c *ConfigWriter) PrintListenerSummary(filter ListenerFilter) error {
 		return err
 	}
 
-	verifiedListeners := []*listener.Listener{}
+	verifiedListeners := make([]*listener.Listener, 0, len(listeners))
 	for _, l := range listeners {
 		if filter.Verify(l) {
 			verifiedListeners = append(verifiedListeners, l)
@@ -179,8 +179,9 @@ var (
 )
 
 func retrieveListenerMatches(l *listener.Listener) []filterchain {
-	resp := []filterchain{}
-	for _, filterChain := range l.GetFilterChains() {
+	fChains := l.GetFilterChains()
+	resp := make([]filterchain, 0, len(fChains))
+	for _, filterChain := range fChains {
 		match := filterChain.FilterChainMatch
 		if match == nil {
 			match = &listener.FilterChainMatch{}
@@ -323,7 +324,7 @@ func describeDomains(vh *route.VirtualHost) string {
 }
 
 func describeRoutes(vh *route.VirtualHost) string {
-	routes := []string{}
+	routes := make([]string, 0, len(vh.GetRoutes()))
 	for _, route := range vh.GetRoutes() {
 		routes = append(routes, describeMatch(route.GetMatch()))
 	}

diff --git a/istioctl/pkg/writer/envoy/configdump/route.go b/istioctl/pkg/writer/envoy/configdump/route.go
@@ -137,7 +137,7 @@ func (c *ConfigWriter) PrintRouteDump(filter RouteFilter) error {
 	if err != nil {
 		return err
 	}
-	filteredRoutes := protio.MessageSlice{}
+	filteredRoutes := make(protio.MessageSlice, 0, len(routes))
 	for _, route := range routes {
 		if filter.Verify(route) {
 			filteredRoutes = append(filteredRoutes, route)

diff --git a/istioctl/pkg/writer/pilot/status.go b/istioctl/pkg/writer/pilot/status.go
@@ -89,7 +89,7 @@ func (s *StatusWriter) PrintSingle(statuses map[string][]byte, proxyName string)
 func (s *StatusWriter) setupStatusPrint(statuses map[string][]byte) (*tabwriter.Writer, []*writerStatus, error) {
 	w := new(tabwriter.Writer).Init(s.Writer, 0, 8, 5, ' ', 0)
 	_, _ = fmt.Fprintln(w, "NAME\tCDS\tLDS\tEDS\tRDS\tISTIOD\tVERSION")
-	var fullStatus []*writerStatus
+	fullStatus := make([]*writerStatus, 0, len(statuses))
 	for pilot, status := range statuses {
 		var ss []*writerStatus
 		err := json.Unmarshal(status, &ss)

diff --git a/operator/pkg/util/progress/progress.go b/operator/pkg/util/progress/progress.go
@@ -59,8 +59,8 @@ const inProgress = `{{ yellow (cycle . "-" "-" "-" " ") }} `
 // createStatus will return a string to report the current status.
 // ex: - Processing resources for components. Waiting for foo, bar
 func (p *Log) createStatus(maxWidth int) string {
-	comps := []string{}
-	wait := []string{}
+	comps := make([]string, 0, len(p.components))
+	wait := make([]string, 0, len(p.components))
 	for c, l := range p.components {
 		comps = append(comps, name.UserFacingComponentName(name.ComponentName(c)))
 		wait = append(wait, l.waiting...)

diff --git a/pilot/pkg/model/push_context.go b/pilot/pkg/model/push_context.go
@@ -1555,7 +1555,7 @@ func (ps *PushContext) initMeshNetworks() {
 		}
 
 		registryNames := getNetworkRegistries(networkConf)
-		gateways := []*Gateway{}
+		gateways := make([]*Gateway, 0, len(gws))
 
 		for _, gw := range gws {
 			gateways = append(gateways, getGatewayAddresses(gw, registryNames, ps.ServiceDiscovery)...)
@@ -1571,7 +1571,7 @@ func (ps *PushContext) initMeshNetworks() {
 func (ps *PushContext) initClusterLocalHosts(e *Environment) {
 	// Create the default list of cluster-local hosts.
 	domainSuffix := e.GetDomainSuffix()
-	defaultClusterLocalHosts := make([]host.Name, 0, len(defaultClusterLocalNamespaces))
+	defaultClusterLocalHosts := make([]host.Name, 0)
 	for _, n := range defaultClusterLocalNamespaces {
 		defaultClusterLocalHosts = append(defaultClusterLocalHosts, host.Name("*."+n+".svc."+domainSuffix))
 	}
@@ -1617,7 +1617,7 @@ func (ps *PushContext) initClusterLocalHosts(e *Environment) {
 }
 
 func getNetworkRegistries(network *meshconfig.Network) []string {
-	var registryNames []string
+	registryNames := make([]string, 0, len(network.Endpoints))
 	for _, eps := range network.Endpoints {
 		if eps != nil && len(eps.GetFromRegistry()) > 0 {
 			registryNames = append(registryNames, eps.GetFromRegistry())

diff --git a/pilot/pkg/serviceregistry/aggregate/controller.go b/pilot/pkg/serviceregistry/aggregate/controller.go
@@ -373,7 +373,7 @@ func (c *Controller) GetIstioServiceAccounts(svc *model.Service, ports []int) []
 			out[sa] = struct{}{}
 		}
 	}
-	result := []string{}
+	result := make([]string, 0, len(out))
 	for k := range out {
 		result = append(result, k)
 	}
@@ -385,7 +385,7 @@ func (c *Controller) GetIstioServiceAccounts(svc *model.Service, ports []int) []
 		}
 	}
 	expanded := spiffe.ExpandWithTrustDomains(result, tds)
-	result = []string{}
+	result = make([]string, 0, len(expanded))
 	for k := range expanded {
 		result = append(result, k)
 	}

diff --git a/pilot/pkg/xds/ads.go b/pilot/pkg/xds/ads.go
@@ -734,7 +734,7 @@ func (s *DiscoveryServer) startPush(req *model.PushRequest) {
 	s.adsClientsMutex.RLock()
 
 	// Create a temp map to avoid locking the add/remove
-	pending := []*Connection{}
+	pending := make([]*Connection, 0, len(s.adsClients))
 	for _, v := range s.adsClients {
 		pending = append(pending, v)
 	}

diff --git a/pkg/adsc/adsc.go b/pkg/adsc/adsc.go
@@ -719,7 +719,7 @@ func (a *ADSC) Save(base string) error {
 
 func (a *ADSC) handleCDS(ll []*cluster.Cluster) {
 
-	cn := []string{}
+	cn := make([]string, 0, len(ll))
 	cdsSize := 0
 	edscds := map[string]*cluster.Cluster{}
 	cds := map[string]*cluster.Cluster{}

diff --git a/tools/istio-iptables/pkg/cmd/format.go b/tools/istio-iptables/pkg/cmd/format.go
@@ -17,7 +17,7 @@ package cmd
 import "strings"
 
 func FormatIptablesCommands(commands [][]string) []string {
-	output := make([]string, 0)
+	output := make([]string, 0, len(commands))
 	for _, cmd := range commands {
 		output = append(output, strings.Join(cmd, " "))
 	}