Azure Storage api doesn't work for asnyc uploads - asp.net-mvc

Question

I am trying to upload so many files via Azure Blob Storage .NET api and using with the current latest version 4.0.1. In ASP.NET MVC application i use async action method to upload via await blobFile.UploadFromStreamAsync but it really doesn't work and even i don't see an exception. It silently stops in that method without success.
But if i change action method to none-async and upload via blobFile.UploadFromStream method then everything to works well. I may uploaded via async way with 1% success rate that means very very low stability.
Do you experience same thing ? Is it bug in Storage Api implementation ?
Here is short example. One is async and the other one is none async action methods. There is no any problem if i upload small files but problem appears on large downloads. In this example UploadBlobSec method upload in short time but UploadBlob takes endless time.
public async Task UploadBlob()
{
var storageAccount = CloudStorageAccount.Parse(ConfigurationManager.ConnectionStrings["AzureStorage"].ConnectionString);
var blobContainer = storageAccount.CreateCloudBlobClient().GetContainerReference("files");
var blobFile = blobContainer.GetBlockBlobReference("song.mp3");
using (var stream = new WebClient().OpenRead("http://apolyonstorage.blob.core.windows.net/files/e8b1a1fa-8791-44dc-92ce-1a67a62f7b0f.mp3"))
{
await blobFile.UploadFromStreamAsync(stream);
}
}
public void UploadBlobSec()
{
var storageAccount = CloudStorageAccount.Parse(ConfigurationManager.ConnectionStrings["AzureStorage"].ConnectionString);
var blobContainer = storageAccount.CreateCloudBlobClient().GetContainerReference("files");
var blobFile = blobContainer.GetBlockBlobReference("song.mp3");
using (var stream = new WebClient().OpenRead("http://apolyonstorage.blob.core.windows.net/files/e8b1a1fa-8791-44dc-92ce-1a67a62f7b0f.mp3"))
{
blobFile.UploadFromStream(stream);
}
}

Answer 1

Code snippet looks fine - although I am not sure what the application around it is doing. Have you turned on server logs to see what is happening server side? For large files you should see the async upload translated into a couple of PutBlocks and then a PutBlockList. If you don't see the PutBlockList them maybe something strange is happening in your application.
Then assuming you do see the operations in the server logs that obviously means the operations are occurring. At that point look at the E2ELatency numbers vs ServerLatency I think you will see a large difference with E2Latency being much higher as it incorporates the time spent client side - and it would be interesting to see if your client network could be contributing to the problem. For example on my connection the e2elatency on the first PutBlock was 1346 ms vs 137 for ServerLatency.
For more information on logging take a look here.
Jason