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, 9 insertions, 0 deletions

diff --git a/src/node_options.cc b/src/node_options.cc
index a6d7e41e8d..a36666c3e0 100644
--- a/src/node_options.cc
+++ b/src/node_options.cc
@@ -161,6 +161,11 @@ void EnvironmentOptions::CheckOptions(std::vector<std::string>* errors) {
     if (!cpu_prof_dir.empty()) {
       errors->push_back("--cpu-prof-dir must be used with --cpu-prof");
     }
+    // We can't catch the case where the value passed is the default value,
+    // then the option just becomes a noop which is fine.
+    if (cpu_prof_interval != kDefaultCpuProfInterval) {
+      errors->push_back("--cpu-prof-interval must be used with --cpu-prof");
+    }
   }
 
   debug_options_.CheckOptions(errors);
@@ -356,6 +361,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "specified file name of the V8 CPU profile generated with "
             "--cpu-prof",
             &EnvironmentOptions::cpu_prof_name);
+  AddOption("--cpu-prof-interval",
+            "specified sampling interval in microseconds for the V8 CPU "
+            "profile generated with --cpu-prof. (default: 1000)",
+            &EnvironmentOptions::cpu_prof_interval);
   AddOption("--cpu-prof-dir",
             "Directory where the V8 profiles generated by --cpu-prof will be "
             "placed. Does not affect --prof.",