C# List - list can be filled or taken from two threads

Question

Hello,

static object LockPackageList = new object();

void Test1()
{    
    lock (LockPackageList)
    {
     switch (type)
     {
     case L.FiFo:
     ListPackageLabel.Add(currentPackage);
     // BlockingCollectionPackage.Add(currentPackage);
     break;
     case L.LiFo:
     ListPackageLabel.Insert(0, currentPackage);
     break;
     }
    }
}

public void DeletePackage()
        {
            lock (LockPackageList)
            {
                ListPackageLabel.RemoveAt(0);
            }

Is that sufficient with the lock?

Need I one static object LockPackageList = new object();
or two?
For Add and Remove?

Answer 1

Hello @Markus Freitag

Have you considered using a thread-safe Singleton? The following is based off this web page sixth version.

public class Address  
{  
    public string Type { get; set; }  
    public string Company { get; set; }  
    public string Number { get; set; }  
    public string Street { get; set; }  
    public string City { get; set; }  
}  

public partial class Person  
{  
    public int Id { get; set; }  
    public string FirstName { get; set; }  
    public string LastName { get; set; }  
    public DateTime? DateOfBirth { get; set; }  
    public IList<Address> Addresses { get; set; }     
}  

Singleton

public sealed class Sample  
{  
    private static readonly Lazy<Sample> Lazy =  
        new Lazy<Sample>(() =>  
            new Sample());  
  
    /// <summary>  
    /// Entry point to access information in this class  
    /// </summary>  
    public static Sample Instance => Lazy.Value;  
    public List<Person> People { get; set; }  
  
    private Sample()  
    {  
        People = new List<Person>();  
    }  
}  

Add in one thread

Sample.Instance.People.Add(new Person() {FirstName = "Karen", LastName = "Payne"});  

Read in another thread (or add etc if you want)

foreach (var person in Sample.Instance.People)  
{  
    Console.WriteLine($"{person.FirstName} {person.LastName}");  
}