为了解释我的问题,如果我从不写共享变量,是否需要任何锁定？

public class CustomerClass
{
    private Config cfg = (Config)ConfigurationManager.GetSection("Customer");

    public void Run()
    {
        var serviceGroups = this.cfg.ServiceDeskGroups.Select(n => n.Group).ToList();

        var groupedData = DataReader.GetSourceData().AsEnumerable().GroupBy(n => n.Field<int>("ID"));
        Parallel.ForEach<IGrouping<int,DataRow>,CustomerDataContext>(
            groupedData,() => new CustomerDataContext(),(g,_,ctx) =>
            {
                var inter = this.FindOrCreateInteraction(ctx,g.Key);

                inter.ID = g.Key;
                inter.Title = g.First().Field<string>("Title");

                this.CalculateSomeProperty(ref inter,serviceGroups);

                return ctx;
            },ctx => ctx.SubmitAllChanges());
    }

    private Interaction FindOrCreateInteraction(CustomerDataContext ctx,int ID)
    {
        var inter = ctx.Interactions.Where(n => n.Id = ID).SingleOrDefault();

        if (inter == null)
        {
            inter = new Interaction();
            ctx.InsertOnSubmit(inter);
        }

        return inter;
    }

    private void CalculateSomeProperty(ref Interaction inter,IEnumerable<string> serviceDeskGroups)
    {
        // Reads from the List<T> class instance variable. Changes the state of the ref'd object.
        if (serviceGroups.Contains(inter.Group))
        {
            inter.Ours = true;
        }
    }
}