feat(server): add net/http/pprof endpoints

Add some basic profiling endpoints over http to start digging into
memory and request latencies.

Documentation/profiling.md

@@ -0,0 +1,24 @@
+## Profiling
+
+etcd exposes profiling information from the Go pprof package over HTTP.
+The basic browseable interface can be found at `http://127.0.0.1:4001/debug/pprof`.
+
+### Heap memory profile
+
+```
+go tool pprof ./bin/etcd http://127.0.0.1:4001/debug/pprof/heap
+```
+
+### CPU profile
+
+```
+go tool pprof ./bin/etcd http://127.0.0.1:4001/debug/pprof/profile
+```
+
+### Blocked goroutine profile
+
+```
+go tool pprof ./bin/etcd http://127.0.0.1:4001/debug/pprof/block
+```
+
+For more information on using the tools see http://blog.golang.org/profiling-go-programs

server/server.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"net/http/pprof"
 	"strings"
 	"time"
 
@@ -62,6 +63,7 @@ func New(name string, urlStr string, bindAddr string, tlsConf *TLSConfig, tlsInf
 	s.installV1()
 	s.installV2()
 	s.installMod()
+	s.installDebug()
 
 	return s
 }
@@ -138,6 +140,14 @@ func (s *Server) installMod() {
 	r.PathPrefix("/mod").Handler(http.StripPrefix("/mod", mod.HttpHandler(s.url)))
 }
 
+func (s *Server) installDebug() {
+	s.router.HandleFunc("/debug/pprof", pprof.Index)
+	s.router.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
+	s.router.HandleFunc("/debug/pprof/profile", pprof.Profile)
+	s.router.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
+	s.router.HandleFunc("/debug/pprof/{name}", pprof.Index)
+}
+
 // Adds a v1 server handler to the router.
 func (s *Server) handleFuncV1(path string, f func(http.ResponseWriter, *http.Request, v1.Server) error) *mux.Route {
 	return s.handleFunc(path, func(w http.ResponseWriter, req *http.Request) error {