Analog jmeter on nodejs

Viktor Sidorenko

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Mar 26, 2015, 3:04:07 PM3/26/15

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Hello all.

I'm create simple client for burst check web server:

var http = require("http");

var req_total = 10,
    req_per_sec = 30,
    i = 0;

var intervalID = setInterval(function timerik()  {
    i++;
    console.log(i); //write to console  task number
    console.time(i + ' latency');

    if(i == req_total){
        clearInterval(intervalID); //end of Life
    }

    http.get("http://www.yandex.ru", function (response){
        console.log(i +" result = " + response.statusCode); //write to console task number and statusCode
        console.timeEnd(i +' latency'); //write to console operation timeout
    });

}, 1000/req_per_sec);

Result:

"C:\Program Files\nodejs\node.exe" run4.js
1
2
3
3 result = 200
3 latency: 24ms
4
4 result = 200
4 latency: 11ms
4 result = 200
4 latency: 43ms
5
6
6 result = 200
6 latency: 12ms
7
7 result = 200
7 latency: 8ms
8
9
10

Process finished with exit code 0

In this try i have two problems:

1) I lose few queries, In result you can see only 5 of 10 queries.

2) Few queries have not valid id. You can see them in result line 4.

How i can fix this problems?

Ruben Rodriguez (cha0s)

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Mar 26, 2015, 4:03:22 PM3/26/15

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It's due to the way you're closing over the variable `i`. `i` is being incremented even if a request takes longer than the interval, so when the request comes back, `i` will be out of sync.

Here's a simple fix, you could approach it many other ways:

var http = require("http");

var req_total = 10,
req_per_sec = 30,
i = 0;

var intervalID = setInterval(function timerik() {

   // Create a new local variable bound to this closure's invocation's scope.
   var j = ++i;

   if(j == req_total){
       clearInterval(intervalID); //end of Life
   }

   console.log(j); //write to console task number
   console.time(j + ' latency');

http.get("http://www.yandex.ru", function (response){

      console.log(j +" result = " + response.statusCode); //write to console task number and statusCode
      console.timeEnd(j +' latency'); //write to console operation timeout
   });

}, 1000/req_per_sec);

Notice all instances of `i` are replaced with a new local variable `j` that is bound to each invocation of the closure's scope.

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Viktor Sidorenko

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Mar 27, 2015, 1:01:53 PM3/27/15

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You all right! first problem fixed.

What do you think about second problem? loss results

Now when i run script i have result only few queries.

"C:\Program Files\nodejs\node.exe" run4.js
1
2
3

1 result = 200
1 latency: 111ms
4
2 result = 200
2 latency: 95ms
5
3 result = 200
3 latency: 99ms
6
4 result = 200
4 latency: 109ms
7
5 result = 200
5 latency: 105ms

8
9
10

Process finished with exit code 0

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