Question

Scenario: a i have an app that makes connection with a SFTP server and download a file. The code that do this:

while (true)
{
    try
    {
        var connectionInfo = // creating a new connection info of a Renci.SshNet lib
        var client = new SftpClient(connectionInfo);
        client.Connect();

        using (SftpFileStream sftpFileStream = client.OpenRead(path)
        {
            using (FileStream fileStream = new FileStream(filePath, FileMode.CreateNew))
            {
                int BUFFER_SIZE = 2048;
                byte[] buffer = new byte[BUFFER_SIZE];

                int readBytes = sftpFileStream.Read(buffer, 0, BUFFER_SIZE);

                while (readBytes > 0)
                {
                    fileStream.Write(buffer, 0, readBytes);
                    readBytes = sftpFileStream.Read(buffer, 0, BUFFER_SIZE);
                }
            }
        }

        client.Dispose();
    }
    catch (Exception e)
    {
        log.Error(e);
    }

    Thread.Sleep(1 hour);
}

In the line client.Connect() a first error was raised:


Renci.SshNet.Common.SftpPathNotFoundException: No such file at Renci.SshNet.Sftp.SubsystemSession.WaitHandle(WaitHandle waitHandle, TimeSpan operationTimeout) at Renci.SshNet.Sftp.SftpSession.RequestOpen(String path, Flags flags, Boolean nullOnError) at Renci.SshNet.Sftp.SftpFileStream..ctor(SftpSession session, String path, FileMode mode, FileAccess access, Int32 bufferSize, Boolean useAsync) at Renci.SshNet.Sftp.SftpFileStream..ctor(SftpSession session, String path, FileMode mode, FileAccess access) at Renci.SshNet.SftpClient.OpenRead(String path) at Infraero.TINE3.STTColetor.Negocio.Drivers.DriverAbstratoArquivoFTP.BaixarArquivoPABXSFTP(ConfiguracaoColetor configuracaoColetor, String arquivoPABX) in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.Negocio\Drivers\DriverAbstratoArquivoFTP.cs:line 446 at Infraero.TINE3.STTColetor.Negocio.Drivers.DriverAbstratoArquivoFTP.ProcessarArquivoSFTP(SftpFile arquivo, ConfiguracaoColetor configuracaoColetor, List'1 listaBilhetes) in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.Negocio\Drivers\DriverAbstratoArquivoFTP.cs:line 658 at Infraero.TINE3.STTColetor.Negocio.Drivers.DriverAbstratoArquivoFTP.ColetarBilhetes(ConfiguracaoColetor configuracaoColetor, List'1 listaBilhetes, String ultimoArquivoTransmitido) in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.Negocio\Drivers\DriverAbstratoArquivoFTP.cs:line 73 at Infraero.TINE3.STTColetor.Negocio.Coletor.ColetarBilhetes() in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.Negocio\Coletor.cs:line 56 at Infraero.TINE3.STTColetor.WindowsService.ServicoColetor..ctor() in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.WindowsService\ServicoColetor.cs:line 85

After 1 hour the process try download the file again, but raises a new error in line client.Connect():


System.Threading.Tasks.TaskSchedulerException: An exception was thrown by a TaskScheduler. ---> System.OutOfMemoryException: Exception of type 'System.OutOfMemoryException' was thrown. at System.Threading.Thread.StartInternal(IPrincipal principal, StackCrawlMark& stackMark) at System.Threading.Thread.Start(StackCrawlMark& stackMark) at System.Threading.Thread.Start(Object parameter) at System.Threading.Tasks.ThreadPoolTaskScheduler.QueueTask(Task task) at System.Threading.Tasks.Task.ScheduleAndStart(Boolean needsProtection) --- End of inner exception stack trace --- at System.Threading.Tasks.Task.ScheduleAndStart(Boolean needsProtection) at System.Threading.Tasks.Task.InternalStartNew(Task creatingTask, Object action, Object state, CancellationToken cancellationToken, TaskScheduler scheduler, TaskCreationOptions options, InternalTaskOptions internalOptions, StackCrawlMark& stackMark) at System.Threading.Tasks.TaskFactory.StartNew(Action action, TaskCreationOptions creationOptions) at Renci.SshNet.Session.ExecuteThread(Action action) at Renci.SshNet.Session.Connect() at Renci.SshNet.BaseClient.Connect() at Infraero.TINE3.STTColetor.Negocio.Drivers.DriverAbstratoArquivoFTP.ConectarServidorSFTP(String servidor, Int32 porta, String login, String senha) in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.Negocio\Drivers\DriverAbstratoArquivoFTP.cs:line 551 at Infraero.TINE3.STTColetor.Negocio.Drivers.DriverAbstratoArquivoFTP.RequisitarArquivoServidorSFTP(ConfiguracaoColetor configuracaoColetor) in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.Negocio\Drivers\DriverAbstratoArquivoFTP.cs:line 519 at Infraero.TINE3.STTColetor.Negocio.Drivers.DriverAbstratoArquivoFTP.ColetarBilhetes(ConfiguracaoColetor configuracaoColetor, List'1 listaBilhetes, String ultimoArquivoTransmitido) in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.Negocio\Drivers\DriverAbstratoArquivoFTP.cs:line 67 at Infraero.TINE3.STTColetor.Negocio.Coletor.ColetarBilhetes() in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.Negocio\Coletor.cs:line 56 at Infraero.TINE3.STTColetor.WindowsService.ServicoColetor..ctor() in D:\SVN\STT\trunk\3-0_CodigoFonte_Coletor\3-4_SRC\Infraero.TINE3.STTColetor.WindowsService\ServicoColetor.cs:line 85

After 1 day, the second error continues, and the memory usage of the app increased from 60MB to 800MB.

Anyone knows what the problem can be?

Answer 1

A quick glance through the code base of the library that you’re using (http://sshnet.codeplex.com/SourceControl/changeset/view/18974) shows that SftpClient also implements IDisposable, but you’re not cleaning it up or closing it when something fails. You should try something like:

try
{
    var connectionInfo = // something
    using(var client = new SftpClient(connectionInfo))
    {
        client.Connect();
        using(var sftpFileStream = client.OpenRead(path))
        {
            // download the file
        }
    }
}

It may also be a memory leak inside the library that you’re using.