ParallelInsert.cs

Parallel.For(0, 500,
    async index =>
    {
        var product = new Product
        {
            Id = id,
            Stock = index+1
        };
        
        using (var scope = new TransactionScope(
            TransactionScopeAsyncFlowOption.Enabled))
        {
            await Save(product);
            scope.Complete();
        }        
    });