Add pprof server and protect it with an env var

This will allow us to enable pprof in any environment where we need to
keep an eye on what is going on, especially since we need to track down
some race conditions during long runs.

Author: ankur22

main.go

@@ -1,6 +1,11 @@
 package browser
 
 import (
+	"log"
+	"net/http"
+	_ "net/http/pprof" // nolint:gosec
+	"os"
+
 	"github.com/grafana/xk6-browser/api"
 	"github.com/grafana/xk6-browser/chromium"
 	"github.com/grafana/xk6-browser/common"
@@ -37,6 +42,16 @@ var (
 	_ k6modules.Instance = &ModuleInstance{}
 )
 
+func init() {
+	if _, ok := os.LookupEnv("XK6_BROWSER_PPROF"); ok {
+		go func() {
+			address := "localhost:6060"
+			log.Println("Starting http debug server", address)
+			log.Println(http.ListenAndServe(address, nil))
+		}()
+	}
+}
+
 // New returns a pointer to a new RootModule instance.
 func New() *RootModule {
 	return &RootModule{}
@@ -69,16 +84,6 @@ func (mi *ModuleInstance) Exports() k6modules.Exports {
 
 // Launch Chromium with given options.
 func (m *JSModule) Launch(opts goja.Value) api.Browser {
-	/*go func() {
-		f, err := os.Create("./cpu.profile")
-		if err != nil {
-			log.Fatal(err)
-		}
-		pprof.StartCPUProfile(f)
-		defer pprof.StopCPUProfile()
-		<-ctx.Done()
-	}()*/
-
 	ctx := k6ext.WithVU(m.vu.Context(), m.vu)
 	ctx = k6ext.WithCustomMetrics(ctx, m.k6Metrics)