inspector: implement --cpu-prof-interval

This patch implements --cpu-prof-interval to specify the sampling
interval of the CPU profiler started by --cpu-prof from the command
line. Also adjust the interval to 100 in test-cpu-prof.js to make
the test less flaky - it would fail if the time taken to finish
the workload is smaller than the sampling interval, which was
more likely on powerful machines when the interval was 1000.

PR-URL: https://github.com/nodejs/node/pull/27535
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/inspector_profiler.cc b/src/inspector_profiler.cc
index a3739d52b21..2d3f061e987 100644
--- a/src/inspector_profiler.cc
+++ b/src/inspector_profiler.cc
@@ -21,7 +21,6 @@ using v8::Object;
 using v8::String;
 using v8::Value;
 
-using v8_inspector::StringBuffer;
 using v8_inspector::StringView;
 
 #ifdef _WIN32
@@ -254,6 +253,10 @@ MaybeLocal<Object> V8CpuProfilerConnection::GetProfile(Local<Object> result) {
 void V8CpuProfilerConnection::Start() {
   DispatchMessage("Profiler.enable");
   DispatchMessage("Profiler.start");
+  std::string params = R"({ "interval": )";
+  params += std::to_string(env()->cpu_prof_interval());
+  params += " }";
+  DispatchMessage("Profiler.setSamplingInterval", params.c_str());
 }
 
 void V8CpuProfilerConnection::End() {
@@ -304,6 +307,7 @@ void StartProfilers(Environment* env) {
   }
   if (env->options()->cpu_prof) {
     const std::string& dir = env->options()->cpu_prof_dir;
+    env->set_cpu_prof_interval(env->options()->cpu_prof_interval);
     env->set_cpu_prof_dir(dir.empty() ? GetCwd() : dir);
     if (env->options()->cpu_prof_name.empty()) {
       DiagnosticFilename filename(env, "CPU", "cpuprofile");