hier vs flat list

gistfile1.txt

using Azure.Storage.Blobs;
using System;
using System.Collections.Concurrent;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace ListSpeedTest
{
    class Program
    {
        static long _count = 0;
        static long _bytes = 0;
        static SemaphoreSlim _slim;
        static ConcurrentBag<Task> _tasks;

        static async Task Main(string[] args)
        {
            string connection = "";
            string[] containerNames = new string[] { "" };


            foreach (var container in containerNames)
            {
                await StraightList(connection, container);
                await HierList(connection, container);
            }


            Console.WriteLine("done!");
            Console.ReadKey();
        }

        static async Task StraightList(string connection, string container)
        {
            Console.WriteLine($"StraightList for {container} starting.");
            Stopwatch sw = new Stopwatch();
            sw.Start();
            var blobServiceClient = new BlobServiceClient(connection);
            var blobContainerClient = blobServiceClient.GetBlobContainerClient(container);
            _count = 0;
            _bytes = 0;

            await foreach (var item in blobContainerClient.GetBlobsAsync())
            {
                _count++;
                _bytes += item.Properties.ContentLength.GetValueOrDefault();
            }
            sw.Stop();
            Console.WriteLine($"StraightList for {container} finished {_count:N0} files {_bytes:N0} bytes in {sw.Elapsed.TotalSeconds:N0} seconds.");
        }



        static async Task HierList(string connection, string container)
        {
            Console.WriteLine($"HierList for {container} starting.");
            Stopwatch sw = new Stopwatch();
            sw.Start();

            _count = 0;
            _bytes = 0;
            _slim = new SemaphoreSlim(Environment.ProcessorCount * 8);
            _tasks = new ConcurrentBag<Task>();

            ProcessFolder(connection, container, "");

            //wait for enough to get the todo list so we don't exit before we started
            await Task.Delay(1000);

            // wait while there are any tasks that have not finished
            while (_tasks.Any(x => !x.IsCompleted))
            {
                Console.WriteLine("Waiting to finish.");
                await Task.Delay(10000);
            }

            sw.Stop();
            Console.WriteLine($"HierList for {container} finished {_count:N0} files {_bytes:N0} bytes in {sw.Elapsed.TotalSeconds:N0} seconds.");
        }

        static void ProcessFolder(string connection, string container, string folder)
        {
            _tasks.Add(Task.Run(async () => {

                await _slim.WaitAsync();

                Console.WriteLine($"ProcessingFolder '{folder}'");

                var blobServiceClient = new BlobServiceClient(connection);
                var blobContainerClient = blobServiceClient.GetBlobContainerClient(container);

                await foreach (var item in blobContainerClient.GetBlobsByHierarchyAsync(prefix: folder, delimiter: "/"))
                {

                    if (item.IsPrefix)
                    {
                        ProcessFolder(connection, container, item.Prefix); 
                    }
                    else
                    {
                        Interlocked.Add(ref _count, 1);
                        Interlocked.Add(ref _bytes, item.Blob.Properties.ContentLength.GetValueOrDefault());
                    }

                }

                _slim.Release();

            }));
        }

    }
}