Archive for July 2010

LINQ-To-SQL Improving Performance

July 25, 2010 C#, LINQ, Tips 2 comments

Linq to SQL is great. I love it because it adds a simple abstraction layer that can greatly speed up building a data access layer.

If not used properly, LINQ to SQL can also create performance issues. Here are my general LINQ to SQL guidelines when I work in projects:


Use the “using” statement when working with a context

This is mostly a general C# programming guideline but there have been several times when I see programmers missing this step. Here is more information from MSDN.

The using statement allows the programmer to specify when objects that use resources should release them. The object provided to the using statement must implement the IDisposable interface. This interface provides the Dispose method, which should release the object’s resources.

A using statement can be exited either when the end of the using statement is reached or if an exception is thrown and control leaves the statement block before the end of the statement.

Here is an example:

using (NorthwindDataContext context = new NorthwindDataContext())
{
  //do stuff here
}


Compiled queries

To query something with LINQ to SQL there are several “startup” procedures. This procedures are not too bad when queries are not used too often. If the same query is done several times, its heavy and it is the core of the product then it is VERY important to make it a compiled query.

I will not go into too many details about this because there are several posts about the subject:


Use multiple tiny contexts instead of big bulky ones

Contexts are meant to keep track of the objects in the database. By having small contexts with a single purpose then the burden of tracking is lessen and therefore there is less memory consumption.


Do not keep track of object changes in the database unless its needed

There are two good ways to improve the performance of queries that do not involve concurrency issues:

  1. Optimistic concurrency  = off
  2. Object tracking = off

For object tracking, is super easy to turn off:

context.ObjectTrackingEnabled = false;

Sadly, as  Rick Strahl covers in his blog there are a few things/issues to consider when turning off Object Tracking.


Combine Queries and custom expressions

Combining queries is a good idea when working with databases, just grab what you need and aggregate the data into a POCO model or anonymous type. Finally, if extreme fine control is needed, there is always custom expressions.

TeamCity Agent has unregistered (will upgrade)

July 24, 2010 Tips One comment

Recently I was setting up Teamcity and the build agent kept going down. It was starting and stopping. Sometimes it was “starting…” for a long time.

After doing a bit of research I came across this. The agents would appear only for seconds under team city and then go down as inactive with the message “Agent has unregistered (will upgrade)”. The culprit was my antivirus. Apparently this is a common issue but I have not seen many people blog about it.

Measuring Quality

July 16, 2010 Software Engineering, Software Management No comments

Many developers forget that in our industry almost everything we do is a service. We are performing work for others at some level. In many cases there will errors in the service provided and then it is when we can measure the quality of the service.

In my opinion, it is an error to try to rate quality of a service as a relation between bugs and release version (this measures how effective are processes). I like to measure quality as a fixed bugs, release version and days to release correlation. This way, we can measure how good is the service by measuring how fast the bugs can be fixed (and properly fixed).

I am not a fan of the even if version 1 sucks, ship it anyway theory but it has some good points. Most of the clients that love my work are happy because any bugs that appeared on the systems have been fixed fast (and remain fixed).

Even google services go down but we all keep using them because google fixes them right away. How can one measure how good is a service? It can be measured by how fast it can respond to change.

Sophos and SVN

July 3, 2010 Tips No comments

If you use Sophos Antivirus you might be getting Tortoise SVN related erros. It took me a while to figure it out. The best way to fix it is to exclude your projects directory from Sophos active scan.

StructureMap Multiple Parameters

July 3, 2010 Inversion of Control, StructureMap No comments

One of the common questions about IOC is how to pass parameters. This question is specially common with StructureMap since a lot of the old methods have been deprecated.

Here is a quick Example:


public class DataSource : IDataSource
{
        public DataSource(string URL, string account, string password)
        {
                     //your code here
         }

}


ObjectFactory.Initialize(x =>
{
      x.For<IDataSource>().Use<DataSource>()
           .Ctor<string>("URL").Is(URL)
           .Ctor<string>("account").Is(account)
           .Ctor<string>("password").Is(password)
           ;
}

and you can call it like this:


private IDataSource ds = ObjectFactory.GetInstance<IDataSource>();

There is a huge amount of benefits as I mentioned in my previous post, including saving a lot of typing since all parameters are preconfigured.

VLC Performance

July 2, 2010 Video No comments

I was not a big fan of VLC. It felt a bit slow and it did not seem to render as smothly as MPC.

Now that with the latest release of VLC that has truly changed. VLC 1.1.0 meets all my expectations. They did an excelent job with the GPU and DSP decoding.

Here is the developers log from GIT: http://git.videolan.org/?p=vlc/vlc-1.1.git;a=tag;h=1.1.0

VLC 1.1.0 - ‘The Luggage’
The first release of the 1.1.x branch of VLC

This is a major release, adding major features, notably:
- GPU and DSP decoding on selected platforms
- New support for codecs, demuxers and muxers
- Lua extensions and Lua content extensions (luaSD)
- Improved interfaces
- Video Output rework
- Removal of lots of modules, rewrite of many
- Improved performances, in CPU, RAM and I/O
- New libVLC and bindings
- New or improved ports on misc platforms
And so many bugs and other features…