The code snippet is a gauge of writing a piece of information to a file in an asynchronous way

WriteAsync.cs

Task.Run(ProcessWriteAsync); // main function call

async Task ProcessWriteAsync()
{
    string baseDirectory = AppDomain.CurrentDomain.BaseDirectory;
    string subPath = @"logs\";
    string fileName = $@"chatlogs.txt";

    DirectoryInfo directoryInfo = new(baseDirectory);

    if (directoryInfo is not null)
    {
        if (!directoryInfo.Exists)
        {
            directoryInfo.Create();
        }
        directoryInfo.CreateSubdirectory(subPath);
    }

    await WriteTextAsync(string.Concat(baseDirectory, subPath, fileName), logMsg);
}

async Task WriteTextAsync(string filePath, string text)
{
    byte[] encodedText = Encoding.Unicode.GetBytes(text);

    using var sourceStream =
        new FileStream(
            filePath,
            FileMode.Append, FileAccess.Write, FileShare.None,
            bufferSize: 4096, useAsync: true);

    await sourceStream.WriteAsync(encodedText.AsMemory(0, encodedText.Length));
}