问带有多线程的SSH.NET SSH私钥文件锁定问题

EN

public class SftpService : ISftpService
{
  private static ConnectionInfo _sftpConnectionInfo { get; set; }
  private static readonly string _mediaServerHost = "test";
  private static readonly string _mediaServerUsername = "test";
  private static readonly int _mediaServerPort = 22;
  private static readonly string _privateSshKeyLocation = "test";
  private static readonly string _privateSshKeyPhrase = "test";
  private static readonly string _mediaServerUploadRootLocation = "test";

    public SftpService()
    {

        var authenticationMethod =  new PrivateKeyAuthenticationMethod(_mediaServerUsername, new PrivateKeyFile[]{ 
                new PrivateKeyFile(_privateSshKeyLocation, _privateSshKeyPhrase)
        });


    // Setup Credentials and Server Information
    _sftpConnectionInfo = new ConnectionInfo(_mediaServerHost, _mediaServerPort, _mediaServerUsername,
        authenticationMethod
    );  

  }

  public void UploadResource(Stream fileStream)
  {
    using (var sftp = new SftpClient(_sftpConnectionInfo))
    {
        sftp.Connect();

        //this is not the real path, just showing example
        var path = "abc.txt";

        sftp.UploadFile(fileStream, path, true);

        sftp.Disconnect();
    }
  }
}