Profiling JavaScript* Code in Node.js*

Cookbook

  • 2021
  • 10/01/2021
  • Public Content
Contents

Profiling JavaScript* Code in Node.js*

This recipe provides configuration steps to rebuild
Node.js
* and enable Intel® VTune™ Amplifier performance analysis for your JavaScript code including mixed-mode call stacks containing JS frames and native frames (native code, for example, system libraries or native libraries called from the JavaScript code).

Ingredients

This section lists the hardware and software tools used for the performance analysis scenario.
  • Application
    :
    sample.js
    . The application is used as a demo and not available for download.
  • JavaScript environment
    :
    Node.js
     version 8.0.0 with Chrome* V8 version 5.8.283.41
  • Performance analysis tools
    : Intel VTune Amplifier 2018 - Advanced Hotspots analysis
    • Starting with the 2020 release, Intel® VTune™ Amplifier has been renamed to
      Intel® VTune™
      Profiler
      .
    • Most recipes in the
      Intel® VTune™
      Profiler
       Performance Analysis Cookbook are flexible. You can apply them to different versions of
      Intel® VTune™
      Profiler
      . In some cases, minor adjustments may be required.
    • Get the latest version of
      Intel® VTune™
      Profiler
      :
  • Operating system
    : Windows* 10

Enable VTune Amplifier Support in Node.js

  1. Download
    node.js
     sources (nightly build).
  2. Run the
    vcbuild.bat
     script from the root
    node-v8.0.0
     folder: 
    echo vcbuild.bat enable-vtune
    This script builds
    Node.js
     with the
    VTune
    Profiler
     support to profile JavaScript code.
  • On Linux* systems, avoid using the
    enable-vtune
     flag with the
    fully-static
     configure flag. This combination is not compatible and causes the
    Node.js
     environment to crash.
  • If you use Microsoft Visual Studio* 2015 IDE or higher, make sure to add
    #define _SILENCE_STDEXT_HASH_DEPRECATION_WARNINGS
     to the
    node-v8.0.0-win\deps\v8\src\third_party\vtune\vtune-jit.cc
     file: 
    #include <string.h>

#ifdef WIN32
#define _SILENCE_STDEXT_HASH_DEPRECATION_WARNINGS
#include <hash_map>
using namespace std;
#else
...

Profile JavaScript Code Running in Node.js

This recipe uses a sample JavaScript application: 
function say(word) {
console.log("Calculating ...");
var res = 0;
for (var i = 0; i < 20000; i++) {
  for (var j = 0; j < 20000; j++) {
    res = i * j / 2;
  }
 }
console.log("Done.");
console.log(word);
}

function execute(someFunction, value) {
  someFunction(value);
}

execute(say, "Hello from Node.js!");
To profile this application with the VTune Amplifier:
  1. Launch the VTune Amplifier: 
    amplxe-gui.exe
  2. Click the New Project icon on the toolbar to create a new project.
  3. In the
    Analysis Target
     tab, specify
    node.exe
     in the
    Application
     field and
    sample.js
     in the
    Application parameters
     field:
  4. Switch to the
    Analysis Type
     tab and select the
    Advance Hotspots
     analysis type from the left pane and click
    Start
     to run the analysis.
    Advanced Hotspots analysis was integrated into the generic Hotspots analysis starting with Intel VTune Amplifier 2019, and is available via the Hardware Event-Based Sampling collection mode.
When the analysis is complete, the VTune Amplifier opens the result in the default Hotspots viewpoint. Use the
Bottom-up
 window to explore how the samples are distributed through JavaScript functions. Double-click the function that took the most CPU time to execute to view the source code and identify the hottest code line:

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.