Why is the resulting UV map stretched out when unwrapping my object? So, I've been unwrapping semi-circular objects and this happens:

 

I wanted to know if it is a configuration setting that I'm screwing up or something like that. I can edit it but it is a huge pain, in some tutorials they just work. This is killing me slowly and surely.
The solution is:

In Object Mode: Apply the scale first.

Now you can unwrap it.

See the image below:



Edit: It is a good practice to Apply any transformations (scale, rotaion...)before using any modifier or/and Unwrap.