Fix pprof handlers. (#3533)

Some of the pprof handlers have to be accessed through
pprof.Handler("string"), while some have to be accessed through an
exported var in pprof. We weren't doing the latter before, which meant
some key handlers like Profile weren't available.

cmd/shell.go

@@ -157,19 +157,21 @@ func newScope(addr string, logger blog.Logger) metrics.Scope {
 	registry.MustRegister(prometheus.NewProcessCollector(os.Getpid(), ""))
 
 	mux := http.NewServeMux()
-	// Register each of the available pprof handlers. These are all registered on
+	// Register the available pprof handlers. These are all registered on
 	// DefaultServeMux just by importing pprof, but since we eschew
 	// DefaultServeMux, we need to explicitly register them on our own mux.
-	reg := func(name string) {
-		mux.Handle("/debug/pprof/"+name, pprof.Handler(name))
-	}
-	reg("block")
-	reg("goroutine")
-	reg("heap")
-	reg("mutex")
-	reg("profile")
-	reg("threadcreate")
-	reg("trace")
+	mux.Handle("/debug/pprof/", http.HandlerFunc(pprof.Index))
+	mux.Handle("/debug/pprof/profile", http.HandlerFunc(pprof.Profile))
+	mux.Handle("/debug/pprof/symbol", http.HandlerFunc(pprof.Symbol))
+	mux.Handle("/debug/pprof/trace", http.HandlerFunc(pprof.Trace))
+	// These handlers are defined in runtime/pprof instead of net/http/pprof, and
+	// have to be accessed through net/http/pprof's Handler func.
+	mux.Handle("/debug/pprof/goroutine", pprof.Handler("goroutine"))
+	mux.Handle("/debug/pprof/block", pprof.Handler("block"))
+	mux.Handle("/debug/pprof/heap", pprof.Handler("heap"))
+	mux.Handle("/debug/pprof/mutex", pprof.Handler("mutex"))
+	mux.Handle("/debug/pprof/threadcreate", pprof.Handler("threadcreate"))
+
 	mux.Handle("/debug/vars", expvar.Handler())
 	mux.Handle("/metrics", promhttp.HandlerFor(registry, promhttp.HandlerOpts{
 		ErrorLog: promLogger{logger},