Linq Lamba Expressions Performance Problems SingleOrDefault Super Slow

A few months ago a release my website www.puertovallarta-bienesraices.com for real estate properties in Puerto Vallarta, Jalisco Mexico. In the last few nights I decided to start optimizing the site and noticed huge performance problems when using SubSonic 3 with Linq. I used to use SubSonic 2 on a high traffic site without any problems. However, with Linq I have been having High CPU Peaks and Memory consumption. I throw some webtests/Load tests with Visual Studio 2010 and started noticed the performance issues especially with Linq. No problems with Subsonic since its just a layer to Linq to Sql.

In particular I was surprise with the function .SingleOrDefault() on a single call for a Property it was taking 0.2 seconds on a database with ~4,000 records. The database has already been optimized.

I did some reading and found an article from JD in regards to this issue

http://www.jdconley.com/blog/archive/2007/11/28/linq-to-sql-surprise-performance-hit.aspx

I decided to implement on the Property class the static for delegates:

public static Func> _propertyGetQuery =

SubSonic.Linq.Structure.QueryCompiler.Compile((PropertyRentalDB db, int id) =>

from p in db.Properties

where p.PropertyId == id

select p);

public static Property GetById(int propertyId)

{

var db = new PropertyRentalDB();

Property p = _propertyGetQuery(db, propertyId).SingleOrDefault();

return p;

}

Compile and run Ants performance profiler and the load tests and the performance results here HUGE!

Total hits 71. Average from 0.20 to 0.011.

Now I can go and optimized more of the code where I use similar instances.

However, I think on my next project I will just go back and use SubSonic 2 and forget about Linq.

Time Ago in Words for .NET C#

I saw the need for a C# version of the time_ago_in_words function in Ruby. I translated the code below into C# from my existing post I published for Ruby.

static string TimeAgo(DateTime time)
{
    DateTime startDate = DateTime.Now;
    TimeSpan deltaMinutes = startDate.Subtract(time);
    string distance = string.Empty;
    if (deltaMinutes.TotalMinutes <= (8724 * 60))
    {
        distance = DistanceOfTimeInWords(deltaMinutes.TotalMinutes);
        if (deltaMinutes.Minutes < 0)
        {
            return distance + " from  now";
        }
        else
        {
            return distance + " ago";
        }
    }
    else
    {
        return "on " + time.ToString();
    }
}


static string DistanceOfTimeInWords(double minutes)
{
    if (minutes < 1)
    {
        return "less than a minute";
    }
    else if (minutes < 50)
    {
        return minutes.ToString() + " minutes";
    }
    else if (minutes < 90)
    {
        return "about one hour";
    }
    else if (minutes < 1080)
    {
        return Math.Round(new decimal((minutes / 60))).ToString() + " hours";
    }
    else if (minutes < 1440)
    {
        return "one day";
    }
    else if (minutes < 2880)
    {
        return "about one day";
    }
    else
    {
        return Math.Round(new decimal((minutes / 1440))).ToString() + " days";
    }
}

You can download the complete source here: http://www.box.net/shared/3fmhllxq8g

Strip numbers from String : C# .NET Remove numbers from string

Here is a simple function I created to strip/remove numbers from a string.
I used the regular expressions to check if a char is number.
I choose to use regular expressions than using the Double.TryParse() because I feel RegEx are faster then the TryParse function. I could be wrong but at this point is doing the job.

public string StripNumbers(string input)
{
    Regex regEx = new Regex("[0-9]+");
    StringBuilder sb = new StringBuilder();
    foreach (char a in input)
    {
        if (!regEx.IsMatch(a.ToString()))
        {
            sb.Append(a);
        }
    }

    return sb.ToString();
}

The next steps will be to test performance and find out what method is faster to check for IsNumber().