Merge pull request #36756 from gmarek/contention

Automatic merge from submit-queue

Add a flag allowing contention profiling of the API server

Useful for performance debugging.

cc @smarterclayton @timothysc @lavalamp

```release-note
Add a flag allowing contention profiling of the API server
```

hack/verify-flags/known-flags.txt

@@ -105,6 +105,7 @@ container-port
 container-runtime
 container-runtime-endpoint
 contain-pod-resources
+contention-profiling
 controller-start-interval
 cors-allowed-origins
 cpu-cfs-quota

pkg/genericapiserver/config.go

@@ -24,6 +24,7 @@ import (
 	"os"
 	"path"
 	"regexp"
+	goruntime "runtime"
 	"sort"
 	"strconv"
 	"strings"
@@ -80,6 +81,8 @@ type Config struct {
 	// allow downstream consumers to disable the index route
 	EnableIndex     bool
 	EnableProfiling bool
+	// Requires generic profiling enabled
+	EnableContentionProfiling bool
 	EnableMetrics             bool
 	EnableGarbageCollection   bool
 
@@ -285,6 +288,7 @@ func (c *Config) ApplyOptions(options *options.ServerRunOptions) *Config {
 	c.CorsAllowedOriginList = options.CorsAllowedOriginList
 	c.EnableGarbageCollection = options.EnableGarbageCollection
 	c.EnableProfiling = options.EnableProfiling
+	c.EnableContentionProfiling = options.EnableContentionProfiling
 	c.EnableSwaggerUI = options.EnableSwaggerUI
 	c.ExternalAddress = options.ExternalHost
 	c.MaxRequestsInFlight = options.MaxRequestsInFlight
@@ -462,6 +466,9 @@ func (s *GenericAPIServer) installAPI(c *Config) {
 	}
 	if c.EnableProfiling {
 		routes.Profiling{}.Install(s.HandlerContainer)
+		if c.EnableContentionProfiling {
+			goruntime.SetBlockProfileRate(1)
+		}
 	}
 	if c.EnableMetrics {
 		if c.EnableProfiling {

pkg/genericapiserver/options/server_run_options.go

@@ -83,6 +83,7 @@ type ServerRunOptions struct {
 	AuditLogMaxSize              int
 	EnableGarbageCollection      bool
 	EnableProfiling              bool
+	EnableContentionProfiling    bool
 	EnableSwaggerUI              bool
 	EnableWatchCache             bool
 	EtcdServersOverrides         []string
@@ -139,6 +140,7 @@ func NewServerRunOptions() *ServerRunOptions {
 		DeleteCollectionWorkers:                  1,
 		EnableGarbageCollection:                  true,
 		EnableProfiling:                          true,
+		EnableContentionProfiling:                false,
 		EnableWatchCache:                         true,
 		InsecureBindAddress:                      net.ParseIP("127.0.0.1"),
 		InsecurePort:                             8080,
@@ -347,6 +349,8 @@ func (s *ServerRunOptions) AddUniversalFlags(fs *pflag.FlagSet) {
 
 	fs.BoolVar(&s.EnableProfiling, "profiling", s.EnableProfiling,
 		"Enable profiling via web interface host:port/debug/pprof/")
+	fs.BoolVar(&s.EnableContentionProfiling, "contention-profiling", s.EnableContentionProfiling,
+		"Enable contention profiling. Requires --profiling to be set to work.")
 
 	fs.BoolVar(&s.EnableSwaggerUI, "enable-swagger-ui", s.EnableSwaggerUI,
 		"Enables swagger ui on the apiserver at /swagger-ui")