Lazy<T>

This section will look closer into the Lazy<T> type.

Use the correct LazyThreadSafetyMode option

If you are using Lazy only in a single-threaded manner, you can save some resources when providing either the isThreadSafe parameter or pass in the correct LazyThreadSafetyMode. The default is LazyThreadSafetyMode.ExecutionAndPublication which creates locks to ensure the synchronization.

❌ Bad Use the multi-thread safe version in a single-threaded application.

var instance = new Lazy<MyClass>(() => new MyClass());

✅ Good Pass the isThreadSafe parameter.

var instance = new Lazy<MyClass>(() => new MyClass(), isThreadSafe: false);

✅ Good Pass the correct LazyThreadSafetyMode parameter.

var instance = new Lazy<MyClass>(() => new MyClass(), LazyThreadSafetyMode.None);

Benchmark

public class LazyBenchmark
{
    [Params(
        LazyThreadSafetyMode.None,
        LazyThreadSafetyMode.PublicationOnly,
        LazyThreadSafetyMode.ExecutionAndPublication)]
    public LazyThreadSafetyMode Option { get; set; }

    [Benchmark]
    public int Lazy()
    {
        var lazy = new Lazy<MyClass>(() => new MyClass(), Option);
        return lazy.Value.MyFunc();
    }
}

public class MyClass
{
    public int MyFunc() => 2;
}

Results:

| Method |               Option |     Mean |    Error |   StdDev |
|------- |--------------------- |---------:|---------:|---------:|
|   Lazy |                 None | 28.06 ns | 0.641 ns | 1.797 ns |
|   Lazy |      PublicationOnly | 32.25 ns | 0.676 ns | 1.013 ns |
|   Lazy | Execu(...)ation [23] | 41.82 ns | 0.829 ns | 1.655 ns |