[chore] optional pprof server

.gitignore

@@ -3,4 +3,4 @@ kl
 .DS_Store
 *.log
 *.txt
-cpu.prof
+*.prof

README.md

@@ -176,10 +176,26 @@ kubectl --context k3d-test2 port-forward services/flask-service 5000:5000
 curl http://localhost:5000/status
 ```
 
-To create a cpu profile, set the environment variable `KL_CPU_PROFILE=1`, run the app, then run e.g.
+To run with profiling available, set the environment variable `KL_PPROF_SERVER=1`, run the app, then run e.g.
 
 ```shell
-go tool pprof -http=:8080 cpu.prof
+# web ui for memory profile
+go tool pprof -http=:8080 "http://localhost:6060/debug/pprof/heap"
+
+# web ui for cpu profile
+go tool pprof -http=:8080 "http://localhost:6060/debug/pprof/profile?seconds=15"
+
+# explore memory profile in terminal
+go tool pprof "http://localhost:6060/debug/pprof/heap"
+> top
+> peek ...
+> traces ...
+
+# explore cpu profile in terminal
+go tool pprof "http://localhost:6060/debug/pprof/profile?seconds=15"
+> top
+> peek ...
+> traces ...
 ```
 
 ## Manually Specify the `kl` Version at Build Time

main.go

@@ -1,23 +1,21 @@
 package main
 
 import (
+	"fmt"
 	"github.com/robinovitch61/kl/cmd"
-	"log"
+	"net/http"
+	_ "net/http/pprof" // register pprof endpoints
 	"os"
-	"runtime/pprof"
 )
 
 func main() {
-	if cpuProfile := os.Getenv("KL_CPU_PROFILE"); cpuProfile != "" {
-		f, err := os.Create("cpu.prof")
-		if err != nil {
-			log.Fatal("could not create CPU profile: ", err)
-		}
-		defer f.Close()
-		if err := pprof.StartCPUProfile(f); err != nil {
-			log.Fatal("could not start CPU profile: ", err)
-		}
-		defer pprof.StopCPUProfile()
+	if pprofServer := os.Getenv("KL_PPROF_SERVER"); pprofServer != "" {
+		port := "6060"
+		go func() {
+			if err := http.ListenAndServe(":"+port, nil); err != nil {
+				panic(fmt.Errorf("pprof server failed: %v", err))
+			}
+		}()
 	}
 
 	err := cmd.Execute()