Question

Recently I was having some issues with a singelton class that was lazy initializing a dictionary where a second thread would try to use it before it had actually been populated. So I implemented the variable initialization through the Lazy<T> class.

Here is my code:

private static Dictionary<string, string> GroupDefaults
{
    get { return mGroupDefaults.Value; }
}
private static Lazy<Dictionary<string, string>> mGroupDefaults =
    new Lazy<Dictionary<string,string>>(delegate
    {
        Dictionary<string, string> defaults = new Dictionary<string, string>();
        foreach (KeyValuePair<string, UnitGroup> groupDef in Groups)
            defaults.Add(groupDef.Key, groupDef.Value.First().Key);
        return defaults;
    });

This fixed the problem and now I am considering making this a regular practice of mine to use the Lazy<T> class anywhere I do lazy initialization to avoid any possible threading issues. So basically I would like to know if this is good/common practice? Or will it be detremental to performance or something?

Answer 1

It’s pretty hard to say without knowing what type of performance constraints you have, but in my experience, one-time initialization is rarely a bottleneck (since by definition it only occurs once.) Lazy<T> was written to provide you with this exact service, so I would recommend using it.