How do I measure the execution time of JavaScript code with callbacks

Question

I have a piece of JavaScript code that I am executing using the node js interpreter   for var i   1  i  lt  LIMIT  i        var user         id  i      name   MongoUser      i              db users save user  function err  saved        if err     saved          console log  Error          else         console log  Saved                    How can I measure the time taken by these database insert operations  I could compute the difference of date values after and before this piece of code but that would be incorrect because of the asynchronous nature of the code

User · Answer

There is a method that is designed for this. Check out process.hrtime(); .

So, I basically put this at the top of my app.

var start = process.hrtime();

var elapsed_time = function(note){
    var precision = 3; // 3 decimal places
    var elapsed = process.hrtime(start)[1] / 1000000; // divide by a million to get nano to milli
    console.log(process.hrtime(start)[0] + " s, " + elapsed.toFixed(precision) + " ms - " + note); // print message + time
    start = process.hrtime(); // reset the timer
}

Then I use it to see how long functions take. Here's a basic example that prints the contents of a text file called "output.txt":

var debug = true;
http.createServer(function(request, response) {

    if(debug) console.log("----------------------------------");
    if(debug) elapsed_time("recieved request");

    var send_html = function(err, contents) {
        if(debug) elapsed_time("start send_html()");
        response.writeHead(200, {'Content-Type': 'text/html' } );
        response.end(contents);
        if(debug) elapsed_time("end send_html()");
    }

    if(debug) elapsed_time("start readFile()");
    fs.readFile('output.txt', send_html);
    if(debug) elapsed_time("end readFile()");

}).listen(8080);

Here's a quick test you can run in a terminal (BASH shell):

for i in {1..100}; do echo $i; curl http://localhost:8080/; done

User · Answer

var start    new Date    var counter   0  for var i   1  i  lt  LIMIT  i           counter      db users save  id   i  name    MongoUser      i         function err  saved              if  err     saved   console log  Error              else console log  Saved              if  --counter     0                             var end    new Date                  console log  all users saved in      end-start      milliseconds

User · Answer

Use the Node js console time   and console timeEnd     var i  console time  dbsave     for i   1  i  lt  LIMIT  i         db users save  id   i  name    MongoUser      i         end      end   function err  saved        console log   err     saved    Error   Saved        if --i     1  console timeEnd  dbsave

User · Answer

Old question but for a simple API and light-weight solution  you can use  perfy which uses high-resolution real time  process hrtime  internally   var perfy   require  perfy     function end label        return function  err  saved            console log err    Error     Saved             console log  perfy end label  time        lt           result  seconds milliseconds           for  var i   1  i  lt  LIMIT  i          var label    db-save-    i      perfy start label       lt           start and mark time     db users save   id  i  name   MongoUser      i          end label        Note that each time perfy end label  is called  that instance is auto-destroyed    Disclosure  Wrote this module  inspired by D Deriso s answer  Docs here

User · Answer

I had same issue while moving from AWS to Azure  For express  amp  aws  you can already use  existing time   and timeEnd    For Azure  use this  https   github com manoharreddyporeddy my-nodejs-notes blob master performance timers helper nodejs azure aws js  These time   and timeEnd   use the existing hrtime   function  which give high-resolution real time   Hope this helps

User · Answer

For anyone want to get time elapsed value instead of console output    use process hrtime   as  D Deriso suggestion  below is my simpler approach       function functionToBeMeasured         var startTime   process hrtime           do some task                      var elapsedSeconds   parseHrtimeToSeconds process hrtime startTime        console log  It takes     elapsedSeconds    seconds       function parseHrtimeToSeconds hrtime        var seconds    hrtime 0     hrtime 1    1e9   toFixed 3       return seconds

User · Answer

Invoking console time  label   will record the current time in milliseconds  then later calling console timeEnd  label   will display the duration from that point    The time in milliseconds will be automatically printed alongside the label  so you don t have to make a separate call to console log to print a label   console time  test      some code console timeEnd  test      Prints something like that- gt  test  11374 004ms   For more information  see Mozilla s developer docs on console time

User · Answer

You could also try exectimer  It gives you feedback like  var t   require  quot exectimer quot     var myFunction        var tick   new t tick  quot myFunction quot       tick start          do some processing and end this tick    tick stop          Display the results console log t timers myFunction duration        total duration of all ticks console log t timers myFunction min        minimal tick duration console log t timers myFunction max        maximal tick duration console log t timers myFunction mean        mean tick duration console log t timers myFunction median        median tick duration   edit  There is an even simpler way now to use exectime  Your code could be wrapped like this  var t   require  exectimer    Tick   t Tick   for var i   1  i  lt  LIMIT  i         Tick wrap function saveUsers done            db users save  id   i  name    quot MongoUser   quot    i    quot   quot    function err  saved                if  err     saved   console log  quot Error quot                else console log  quot Saved quot                done                              Display the results console log t timers myFunction duration        total duration of all ticks console log t timers saveUsers min        minimal tick duration console log t timers saveUsers max        maximal tick duration console log t timers saveUsers mean        mean tick duration console log t timers saveUsers median        median tick duration

User · Answer

You could give Benchmark js a try  It supports many platforms among them also node js

User · Answer

Surprised no one had mentioned yet the new built in libraries  Available in Node  gt   8 5  and should be in Modern Browers https   developer mozilla org en-US docs Web API Performance https   nodejs org docs latest-v8 x api perf hooks html  Node 8 5   9 x  Firefox  Chrome   x000D   x000D     const   performance     require  perf hooks       enable for node const delay   time   gt  new Promise res  gt setTimeout res time   async function doSomeLongRunningProcess      await delay 1000     performance mark  A     async     gt     await doSomeLongRunningProcess      performance mark  B      performance measure  A to B    A    B      const measure   performance getEntriesByName  A to B   0        firefox appears to only show second precision    console log measure duration        apparently you should clean up      performance clearMarks      performance clearMeasures                  Prints the number of milliseconds between Mark  A  and Mark  B        x000D   x000D   x000D   https   repl it  CodyGeisler NodeJsPerformanceHooks Node 12 x https   nodejs org docs latest-v12 x api perf hooks html const   PerformanceObserver  performance     require  perf hooks    const delay   time   gt  new Promise res   gt  setTimeout res  time   async function doSomeLongRunningProcess         await delay 1000     const obs   new PerformanceObserver  items    gt        console log  PerformanceObserver A to B  items getEntries   0  duration            apparently you should clean up          performance clearMarks             performance clearMeasures       Not a function in Node js 12     obs observe   entryTypes    measure        performance mark  A      async function main        try          await performance timerify doSomeLongRunningProcess             performance mark  B            performance measure  A to B    A    B         catch e           console log  main   error  e

[javascript] How do I measure the execution time of JavaScript code with callbacks?

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