Lifetime of a Singleton

Question

I'm building a WCF-Service which is hosted in a windows service. The WCF-Service is called by an ASP.Net application by using a proxy.

using (WcfServiceRef.MonitorClient proxy = new WcfServiceRef.MonitorClient())
{
    //WCF Service proxy
    proxy.Open();
    proxy.DoSomething();
}

Furthermore i have a Singleton class DataAdapter which is used in the WCF-service like this (most of the time it simply forwards the call to the DataAdapter, to be able to change the implementation of the actual data-access easily):

DataAdapter.GetInstance().DoSomething();

My DataAdapter looks like this and holds myData which should be kept alive:

public static DataAdapter DataAdapterInstance;
    private List<CustomObjects> myData;

    internal static ServiceAdapter GetInstance()
    {
        if (DataAdapterInstance == null)
        {
            DataAdapterInstance = new DataAdapter();
        }
        return DataAdapterInstance;
    }

Now here comes what im haveing trouble with: (im not sure if everything im writing here is correct)

• The windows service' runs theoretically forever (as it should) The
• WCF-service only runs when it is called/created by my proxy (from asp.net)

When does my DataAdapter (which contains all my data) "die" ... so what im asking here is what is the lifetime of an object when there is actually no reference on it. (i would say its collected whenever the garbage collector runs) - I think my approach isnt too good, i would appreciate any suggestions on how to store my data (preferred without using a DB or external file)

Thank you for looking into my problem!

Answer 1

Static references are "root" references for GC, so they will "never" die (until AppDomain is unloaded)