etcdmain: add an option for pprof

This commit adds a new option for activating profiling based on pprof
in etcd process.
 - -enable-pprof: boolean type option which activates profiling

For example, if a client URL is http://localhost:12379, users and
developers access heap profiler with this URL:
http://localhost:12379/debug/pprof/heap

Documentation/configuration.md

@@ -263,6 +263,12 @@ Follow the instructions when using these flags.
 + Print the version and exit.
 + default: false
 
+## Profiling flags
+
+### -enable-pprof
++ Enable runtime profiling data via HTTP server. Address is at client URL + "/debug/pprof"
++ default: false
+
 [build-cluster]: clustering.md#static
 [reconfig]: runtime-configuration.md
 [discovery]: clustering.md#discovery

etcdmain/config.go

@@ -123,6 +123,8 @@ type config struct {
 	v3demo   bool
 	gRPCAddr string
 
+	enablePprof bool
+
 	ignored []string
 }
 
@@ -230,6 +232,9 @@ func NewConfig() *config {
 	fs.Var(&flags.DeprecatedFlag{Name: "peers"}, "peers", "DEPRECATED: Use -initial-cluster instead.")
 	fs.Var(&flags.DeprecatedFlag{Name: "peers-file"}, "peers-file", "DEPRECATED: Use -initial-cluster instead.")
 
+	// pprof profiler via HTTP
+	fs.BoolVar(&cfg.enablePprof, "enable-pprof", false, "Enable runtime profiling data via HTTP server. Address is at client URL + \"/debug/pprof\"")
+
 	// ignored
 	for _, f := range cfg.ignored {
 		fs.Var(&flags.IgnoredFlag{Name: f}, f, "")

etcdmain/etcd.go

@@ -20,6 +20,7 @@ import (
 	"io/ioutil"
 	"net"
 	"net/http"
+	_ "net/http/pprof"
 	"os"
 	"path"
 	"reflect"
@@ -294,6 +295,7 @@ func startEtcd(cfg *config) (<-chan struct{}, error) {
 		ElectionTicks:       cfg.electionTicks(),
 		V3demo:              cfg.v3demo,
 		StrictReconfigCheck: cfg.strictReconfigCheck,
+		EnablePprof:         cfg.enablePprof,
 	}
 	var s *etcdserver.EtcdServer
 	s, err = etcdserver.NewServer(srvcfg)

etcdmain/help.go

@@ -139,5 +139,9 @@ experimental flags:
 		enable experimental v3 demo API.
 	--experimental-gRPC-addr '127.0.0.1:2378'
 		gRPC address for experimental v3 demo API.
+
+profiling flags:
+	--enable-pprof 'false'
+		Enable runtime profiling data via HTTP server. Address is at client URL + "/debug/pprof"
 `
 )

etcdserver/config.go

@@ -52,6 +52,8 @@ type ServerConfig struct {
 	V3demo bool
 
 	StrictReconfigCheck bool
+
+	EnablePprof bool
 }
 
 // VerifyBootstrapConfig sanity-checks the initial config for bootstrap case

etcdserver/etcdhttp/client.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"net/http/pprof"
 	"net/url"
 	"path"
 	"strconv"
@@ -54,6 +55,7 @@ const (
 	healthPath               = "/health"
 	versionPath              = "/version"
 	configPath               = "/config"
+	pprofPrefix              = "/debug/pprof"
 )
 
 // NewClientHandler generates a muxed http.Handler with the given parameters to serve etcd client requests.
@@ -108,6 +110,23 @@ func NewClientHandler(server *etcdserver.EtcdServer, timeout time.Duration) http
 	mux.Handle(deprecatedMachinesPrefix, dmh)
 	handleAuth(mux, sech)
 
+	if server.IsPprofEnabled() {
+		plog.Infof("pprof is enabled under %s", pprofPrefix)
+
+		mux.HandleFunc(pprofPrefix, pprof.Index)
+		mux.HandleFunc(pprofPrefix+"/profile", pprof.Profile)
+		mux.HandleFunc(pprofPrefix+"/symbol", pprof.Symbol)
+		mux.HandleFunc(pprofPrefix+"/cmdline", pprof.Cmdline)
+		// TODO: currently, we don't create an entry for pprof.Trace,
+		// because go 1.4 doesn't provide it. After support of go 1.4 is dropped,
+		// we should add the entry.
+
+		mux.Handle(pprofPrefix+"/heap", pprof.Handler("heap"))
+		mux.Handle(pprofPrefix+"/goroutine", pprof.Handler("goroutine"))
+		mux.Handle(pprofPrefix+"/threadcreate", pprof.Handler("threadcreate"))
+		mux.Handle(pprofPrefix+"/block", pprof.Handler("block"))
+	}
+
 	return requestLogger(mux)
 }
 

etcdserver/server.go

@@ -844,6 +844,8 @@ func (s *EtcdServer) Lead() uint64 { return atomic.LoadUint64(&s.r.lead) }
 
 func (s *EtcdServer) Leader() types.ID { return types.ID(s.Lead()) }
 
+func (s *EtcdServer) IsPprofEnabled() bool { return s.cfg.EnablePprof }
+
 // configure sends a configuration change through consensus and
 // then waits for it to be applied to the server. It
 // will block until the change is performed or there is an error.