ria services server side data structure: is it shared between threads

Question

So suppose I have ria services DomainDataService class:

public partial class SomeService : LinqToEntitiesDomainService<SomeEntities>
{
    List<string> list = new List<string>();
    public IQueryable<SomeEntity> GetSomeEntity()
    {
       list.Add("test");
       ...
    }
}

There is a global variable list. GetSomeEntity method can obviously be called simultaneously. The question: is list shared between parallel GetSomeEntity invocation, i.e. do I have to protect it with locks? I guess the same applies to all asp.net server side flavors, for instance web services (or not?).

Answer 1

It should depend on the context mode for the service. You can control this via an attribute:

[EnableClientAccess()]
[ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple)]
public partial class SomeService : LinqToEntitiesDomainService<SomeEntities>
{

I believe the default option is ConcurrencyMode.Single.

From MSDN: "Setting ConcurrencyMode to Single instructs the system to restrict instances of the service to one thread of execution at a time, which frees you from dealing with threading issues"

So, to answer your question, the global list is not shared between calls to your service (unless you make is static).