Memory Leak with Microsoft Speech Recognition

Question

I’m having an issue with memory leak when running speech recognition using Microsoft.Speech.Recognition, there appears to be a memory leak issue. The recognition engine constantly grows in memory during execution, even though it is disposed of correctly. The problem is specifically observed in the following code block:

while (!stoppingToken.IsCancellationRequested && !disposed)

{

    Thread.Sleep(100);

    try

    {

        int read = originStream.Read(buffer, 0, 48000);

        bufferedByteStream.Write(buffer, 0, read);

    }

    catch (IOException ex) when (ex.InnerException is SocketException { SocketErrorCode: SocketError.ConnectionReset })

    {

        Console.WriteLine("Connection was forcibly closed by the remote host.");

        bufferedByteStream.Close();

        disposed = true;

    }

}

**Context:**

• The recognition engine grows in memory while it runs in a separate thread.
• Disposing of the engine at the end of the execution does not resolve the issue.
• The memory growth is evident even with correct disposal practices.

**Additional Information:**

• The issue happens withMicrosoft.Speech.Recognition and is also observed in System.Speech.Recognition.
• The code is part of a background service and runs continuously.

**Code Snippet for Reference:**

// ... (previous code)

using (SpeechRecognitionEngine engine = SREBuilder.Create(new[] { "1FriendlyDoge", "notanoob600m", "RoyalCrests" }))

{

  engine.SpeechRecognized += (sender, e) => HandleSpeechRecognized(sender, e, userId, guildId);

  engine.SetInputToAudioStream(bufferedByteStream, new SpeechAudioFormatInfo(EncodingFormat.Pcm, 48000, 16, 2, 192000, 4, null));

  engine.RecognizeAsync(RecognizeMode.Multiple);

    while (!stoppingToken.IsCancellationRequested && !disposed)

    {

        Thread.Sleep(100);

        try

        {

            int read = originStream.Read(buffer, 0, 48000);

            bufferedByteStream.Write(buffer, 0, read);

        }

        catch (IOException ex) when (ex.InnerException is SocketException { SocketErrorCode: SocketError.ConnectionReset })

        {

            Console.WriteLine("Connection was forcibly closed by the remote host.");

            bufferedByteStream.Close();

            disposed = true;

        }

    }

}

For some additional information, the buffered steam is just a list of bytes with a predefined size (48,000 bytes in this case, which is 0.25s of audio data) and its size never changes.

When trying to profile the issue using dotMemory the issue seems to be a ton of Byte[] object with a stack trace of literally just [AllThreadsRoot].

The exception gets called when a socket connection closes (each socket connection has its own instance of SpeechRecognitionEngine) and only happens once per instance. After that everything is being disposed.

If I just comment engine.RecognizeAsync(RecognizeMode.Multiple); out the leak doesnt happen

I have tried to run a more intense GC as well.

Out of ideas right now, help is very much appreciated!

Answer 1

Hello

Thank you for posting in Microsoft Community forum.

I’m sorry to hear that you’re experiencing a memory leak issue with Microsoft.Speech.Recognition. I can help you with some general tips that might help you resolve the issue.

According to a stack over flow post, the memory leak issue you’re experiencing is a known problem with Microsoft.Speech.Recognition and System.Speech.Recognition. The recognition engine grows in memory while it runs in a separate thread, and disposing of the engine at the end of the execution does not resolve the issue. The memory growth is evident even with correct disposal practices.

One possible solution is to use the SpeechRecognitionEngine class instead of Microsoft.Speech.Recognition or System.Speech.Recognition. The SpeechRecognitionEngine class is part of the System.Speech namespace and is designed to work with the .NET Framework 4.0 and later versions. It is recommended to use this class instead of the other two classes.

Another possible solution is to use the PushStream class instead of the MemoryStream class. According to a GitHub issue, the memory leak issue is observed when more than two PushStream instances are used, and it gets worse as more PushStream instances are added. This would suggest that some shared memory managed by the SDK grows as PushStream instances are used.

I hope this information helps you resolve the issue. Let me know if you have any other questions or concerns.

Best Regards,

Zack Lu

Answer 2

Hello

 

Thank you for posting in Microsoft Community forum.

 

I’m sorry to hear that you’re experiencing a memory leak issue with Microsoft.Speech.Recognition. I can help you with some general tips that might help you resolve the issue.

According to a stack over flow post, the memory leak issue you’re experiencing is a known problem with Microsoft.Speech.Recognition and System.Speech.Recognition. The recognition engine grows in memory while it runs in a separate thread, and disposing of the engine at the end of the execution does not resolve the issue. The memory growth is evident even with correct disposal practices.

One possible solution is to use the SpeechRecognitionEngine class instead of Microsoft.Speech.Recognition or System.Speech.Recognition. The SpeechRecognitionEngine class is part of the System.Speech namespace and is designed to work with the .NET Framework 4.0 and later versions. It is recommended to use this class instead of the other two classes.

Another possible solution is to use the PushStream class instead of the MemoryStream class. According to a GitHub issue, the memory leak issue is observed when more than two PushStream instances are used, and it gets worse as more PushStream instances are added. This would suggest that some shared memory managed by the SDK grows as PushStream instances are used.

I hope this information helps you resolve the issue. Let me know if you have any other questions or concerns.

 

 

Best Regards,

Zack Lu

Hi Zack,

You have no idea how much I appreciate someone actually helping me with this! Thank you so much.

Unfortunately, I'm having some trouble following exactly what you are suggesting.

When using .NET Framework v4.8 there is no System.Speech namespace.

I am also unable to find the PushStream documentation.

All I can find is references to Azure Speech for PushStream. Due to the nature of my application, I can't use this. I must use an offline Speech Recognition tool.

I have isolated this even further and am 100% sure this is an issue with the library itself.

Thank you!