High CPU Utilization in Random Pin Generation

Sivasankaran Gurusamy

Hi Team,

We have an application for Random Pin Generation. As per business requirement, we have to support 12 concurrent user transactions at a time. Where in each user will attempt to generate 1 lakh Pins during each transaction. During this activity, application server's CPU utilization reached maximum limit.

We identified, random number generation task is what consuming maximum system resources ( 70 %). please advise where we need betterment to fix this issue? Should we need to find solution in IIS side or Application level?

System Configuration

1. 16 GB RAM

2. OCTA Core Processor

3. IIS 7.0

4. Development Environment ( Visual Studio 4.0)

Code

List lstpins = null;

lstpins = new List();

for (int i = 1; i <= qty; )

{

double dlRnd = rnFirst.NextDouble();//with seed

if (dlRnd < 0.0001)

{

dlRnd += 0.012;

}

string strRndFirstDgt = dlRnd.ToString().Substring(2, iFirstPinLng);

//----Second Rnd ------ 0.6 91979 52919 26617

double dlSecondRnd = rnSecond.NextDouble(); //Without Seed. 58535 03461 123

if (dlSecondRnd < 0.0001)

{

dlSecondRnd += 0.012;

}

string strRndSecondLastsixDgt = dlSecondRnd.ToString().Substring(dlSecondRnd.ToString().Length - iSecondPinLng, iSecondPinLng);

string conCan = strRndFirstDgt + strRndSecondLastsixDgt;

long temp;

temp = Convert.ToInt64(conCan) + DateTime.Now.Ticks; //addition to pin+ datetime Ticks

int intRndThird = rnThird.Next(1, 10);//To avoid the prefix value 0's;

string conCanRnd = intRndThird.ToString() + (temp.ToString().Substring(temp.ToString().Length - pinLength, pinLength - 1));

string sessionconcatpins = stInt + conCanRnd.ToString(); // Append Concurent User Hit Count in to PINS

if (!string.IsNullOrEmpty(sessionconcatpins.Trim()))

{

if (!lstpins.Contains(sessionconcatpins))

{

lstpins.Add(sessionconcatpins);

i++;

}

if (i % 100 == 0)

{

lngDateTicker = DateTime.Now.Ticks;

strSeedLastNineDgt = lngDateTicker.ToString().Substring(7, 9);

rnFirst = new Random(Convert.ToInt32(strSeedLastNineDgt));

}

Thread.Sleep(100);

return lstpins;

2 Replies

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Sivasankaran Gurusamy11y ago
Hi ,

Thanks for your support , we tried with your suggestion , The CPU utilization getting less ..(5%)
Vulpes11y ago
I suspect your problem here is the large number of string operations you're doing, particularly when taking sub-strings of the random doubles to extract digits from them.

This will be both CPU intensive and slow. Worse still the garbage collector will be kicking in periodically to clean up the previously used strings.

What you could try and do is to replace those sub-string operations with a method which extracts digits numerically i.e. without using strings. This should be much quicker to execute and won't require garbage collection.

Here's one I've just written for the purpose (not necessarily the best way of doing this):

using System;

class Program
{
static void Main()
{
double d = 0.717632456901;
for(int i = 2; i < 14; i++)
{
Console.WriteLine(ExtractDigits(d, i, 14 - i));
}
}

static long ExtractDigits(double d, int start, int digits)
{
/* assumes 0 <= d < 1 and start >= 2 */

long powerOfTen = 1;
int count = 1;
if (start > 2) digits += start - 2;

while (count <= digits)
{
powerOfTen *= 10L;
count++;
}

long result = (long)(powerOfTen * (d + 0.000000000000001));

if (start > 2)
{
count = 1;

while (count <= start - 2)
{
powerOfTen /= 10L;
count++;
}

result -= ExtractDigits(d, 2, start - 2) * powerOfTen;
}

return result;
}

The output is:

717632456901
17632456901
7632456901
632456901
32456901
2456901
456901
56901
6901
901
1
1

Notice that the second last extraction is 1 rather than 01 because the method returns a long rather than a string. Not sure whether this will be a problem or not in your application?