FileStreamResult: ObjectDisposedException: Cannot access a disposed object.

[vitali-karmanov]

Hello,

What is the right way of using a RecyclableMemoryStreamManager with FileStreamResult? I'm having the following issue:

public class PdfFileAttachment
{
    public byte[] FileBytes { get; set; }
    public string ContentType { get; set; }
}

PdfFileAttachment pdfFileAttachment = await _pdfService.GetPdfFileAttachment();

var options = new RecyclableMemoryStreamManager.Options()
{
    BlockSize = 1024,
    LargeBufferMultiple = 1024 * 1024,
    MaximumBufferSize = 16 * 1024 * 1024,
    GenerateCallStacks = true,
    AggressiveBufferReturn = true,
    MaximumLargePoolFreeBytes = 16 * 1024 * 1024 * 4,
    MaximumSmallPoolFreeBytes = 100 * 1024,
};

var manager = new RecyclableMemoryStreamManager(options);

using (var memoryStream = manager.GetStream())
{
    memoryStream.Write(pdfFileAttachment.FileBytes, 0, pdfFileAttachment.FileBytes.Length);
    
    return new FileStreamResult(memoryStream, pdfFileAttachment.ContentType);
}

The end goal is to return a pdf file that is stored in a byte[].

Thank you!

[sgorozco]

I think you should remove the using() statement surrounding the manager.GetStream() call - it is automatically disposing the stream before the calling function has a chance to receive the FileStreamResult you are returning.

…

On Wed, Feb 28, 2024 at 6:13 PM Vitali Karmanov ***@***.***> wrote: Hello, What is the right way of using a RecyclableMemoryStreamManager with FileStreamResult? I'm having the following issue: image.png (view on web) <https://github.com/microsoft/Microsoft.IO.RecyclableMemoryStream/assets/40288109/6b439dc8-aed1-440f-9940-6c692bafebf7> public class PdfFileAttachment { public byte[] FileBytes { get; set; } public string ContentType { get; set; } } PdfFileAttachment pdfFileAttachment = await _pdfService.GetPdfFileAttachment(); var options = new RecyclableMemoryStreamManager.Options() { BlockSize = 1024, LargeBufferMultiple = 1024 * 1024, MaximumBufferSize = 16 * 1024 * 1024, GenerateCallStacks = true, AggressiveBufferReturn = true, MaximumLargePoolFreeBytes = 16 * 1024 * 1024 * 4, MaximumSmallPoolFreeBytes = 100 * 1024, }; var manager = new RecyclableMemoryStreamManager(options); using (var memoryStream = manager.GetStream()) { memoryStream.Write(pdfFileAttachment.FileBytes, 0, pdfFileAttachment.FileBytes.Length); return new FileStreamResult(memoryStream, pdfFileAttachment.ContentType); } The end goal is to return a pdf file that is stored in a byte[]. Thank you! — Reply to this email directly, view it on GitHub <#336>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABRR7UX2EOBHM336KWSJQU3YV7BY5AVCNFSM6AAAAABD67C27GVHI2DSMVQWIX3LMV43ASLTON2WKOZSGE3DAMBZGQ2DCOA> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[vitali-karmanov]

If I remove the using and I added pdfFileStream.Seek(0, SeekOrigin.Begin) before the return it works.

public class PdfFileAttachment
{
    public byte[] FileBytes { get; set; }
    public string ContentType { get; set; }
}

PdfFileAttachment pdfFileAttachment = await _pdfService.GetPdfFileAttachment();

var options = new RecyclableMemoryStreamManager.Options()
{
    BlockSize = 1024,
    LargeBufferMultiple = 1024 * 1024,
    MaximumBufferSize = 16 * 1024 * 1024,
    GenerateCallStacks = true,
    AggressiveBufferReturn = true,
    MaximumLargePoolFreeBytes = 16 * 1024 * 1024 * 4,
    MaximumSmallPoolFreeBytes = 100 * 1024,
};

var manager = new RecyclableMemoryStreamManager(options);

var memoryStream = manager.GetStream();

memoryStream.Write(pdfFileAttachment.FileBytes, 0, pdfFileAttachment.FileBytes.Length);

pdfFileStream.Seek(0, SeekOrigin.Begin);

return new FileStreamResult(memoryStream, pdfFileAttachment.ContentType);

However, doesn't removing the using kind of defeat the purpose of the RecyclableMemoryStream by not disposing the stream?

Thank you!

[sgorozco]

When you dispose of the stream, the recyclable buffers, which act as storage for the stream, are returned to their pool. It's important to dispose of the stream, but make sure to do this after you've processed the FileStreamResult you're returning. The Dispose() method call, whether explicit or implicit through the using() statement, should be made from outside the method that creates and returns the FileStreamResult.

[steve-warren]

FileStreamResult is automatically disposed per FileStreamResultExecutor.ExecuteAsync:

https://github.com/dotnet/aspnetcore/blob/d9df235c2e6d41b65d8e860c5e209d9df8cbcae1/src/Mvc/Mvc.Core/src/Infrastructure/FileStreamResultExecutor.cs#L31