Parallelism and Entity Framework

Question

I’m having some problems using parallelism (I don’t have much knowledge in this area) with C# and Entity Framework.

My scenario is as follows, I am using an ASP.NET MVC application and within it I have a list of objects that do various validations. As there are many (more than 45,000 on average) if I wait in a single thread, the delay is great.

For this I thought of working with parallelism, only that I ended up having some problems like dbcontext that I had to instantiate for each thread to be able to work in multiple threads.

I’m using Parallel.Foreach(list, x => Methododevalidation(x).Wait()); to perform the validations asynchronously.

Below my validation method.

public Task MetodoDeValidacao(IEnumerable<Lista> lista) {
     return Task.Factory.StartNew(() =>
     {
       if (!_service.fazAlgumaCoisa(lista))
          ModelState.AddModelError("Model", "Você não fez alguma coisa");
     }
}

My question is : Is this the best way to make validations in parallel? Do you have any articles to recommend?

Answer 1

My question is : This is the best way to make validations in parallel?

Not at all. This is one of the worst, I’d say.

You are creating there the problem of the highlighted context. This code will never work.

First of all, a context is not thread-safe. You need to invoke the lock() before trying to validate.

Second, one does not encapsulate a context within a service and the instance multiple times. The collection as a whole needs to be observable. Therefore it is a context only for N validations.

Instead of using a service, use a static class by referencing the context and locking the context in a critical region when validating.