试图上传到FTP:System.Net.WebException:系统错误

Question

我有一个API,它接受XML并最终根据XML中的信息上传文件.上传按时间表(也来自XML),我测试了它周围的一切,并知道它的工作原理.

我在每个时间周期尝试上传的第一个文件上有大约40%的时间出现错误(某些文件的时间周期= 45分钟,其他文件的时间周期为30分钟).

这是我上传的代码:

try {
    LoggerFTP.Log("Uploading file: " + filename, false);

    // Create the request.
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create(appSettingsFTP.ftpUrl + @"/" + filename);
    request.Method = WebRequestMethods.Ftp.UploadFile;
    request.Timeout = 6000000; //set to 100 minutes
    //request.Timeout = -1; //set to infinite

    // Add the login credentials.
    request.Credentials = new NetworkCredential(appSettingsFTP.ftpLogin, appSettingsFTP.ftpPassword);

    // Grab the file contents.
    StreamReader sourceStream = new StreamReader(appSettingsFTP.uploadFileDirectory + filename);
    byte[] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
    sourceStream.Close();
    request.ContentLength = fileContents.Length;

    // Copy the file contents to the outgoing stream.
    Stream requestStream = request.GetRequestStream();
    requestStream.Write(fileContents, 0, fileContents.Length);
    requestStream.Close();

    FtpWebResponse response = (FtpWebResponse)request.GetResponse();
    //Logger.Log(filename.ToString() + " " + "Upload Complete, Status: " + response.StatusCode + " " + response.StatusDescription, false);
    //Took response.StatusDescription out because it appears to be creating extra line feeds.
    LoggerFTP.Log(filename.ToString() + " " + "Upload Complete, Status: " + response.StatusCode, false);
}
catch (Exception ex) {
    LoggerFTP.Log(ex.ToString(), false);
}

我已经研究过这个问题,并在网上看到了一些关于它可能是速度的事情.就像,有一个超时.但是我的FtpWebRequest的超时设置为100分钟,所以不可能是这样吗？我不知道.这也是作为服务运行的,因此很难测试代码的这个方面.

以下是我的记录器(e.ToString)中记录的异常:

System.Net.WebException: System error. ---> System.Net.InternalException: System error.
   at System.Net.PooledStream.PrePush(Object expectedOwner)
   at System.Net.ConnectionPool.PutConnection(PooledStream pooledStream, Object owningObject, Int32 creationTimeout, Boolean canReuse)
   at System.Net.FtpWebRequest.FinishRequestStage(RequestStage stage)
   at System.Net.FtpWebRequest.SyncRequestCallback(Object obj)
   at System.Net.FtpWebRequest.RequestCallback(Object obj)
   at System.Net.CommandStream.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at System.IO.Stream.Dispose()
   at System.Net.ConnectionPool.Destroy(PooledStream pooledStream)
   at System.Net.ConnectionPool.PutConnection(PooledStream pooledStream, Object owningObject, Int32 creationTimeout, Boolean canReuse)
   at System.Net.FtpWebRequest.AttemptedRecovery(Exception e)
   at System.Net.FtpWebRequest.SubmitRequest(Boolean async)
   --- End of inner exception stack trace ---
   at System.Net.FtpWebRequest.GetRequestStream()
   at CPMainSpringAPIExportsSC.UploadFTP.FTPUploadMethod(String viewname, String filename)

Answer 1

我在尝试通过SSL进行FTP的SSIS包中得到了完全相同的堆栈跟踪。如果没有SSL，它会很好用，但是一旦启用SSL，它就会崩溃。

    System.Net.WebException: System error. --->
    System.Net.InternalException: System error.    at
    System.Net.PooledStream.PrePush(Object expectedOwner)    at
    System.Net.ConnectionPool.PutConnection(PooledStream pooledStream, Object owningObject, Int32 creationTimeout, Boolean canReuse)    at
    System.Net.FtpWebRequest.FinishRequestStage(RequestStage stage)    at
    System.Net.FtpWebRequest.SyncRequestCallback(Object obj)    at
    System.IO.Stream.Close()    at
    System.Net.ConnectionPool.Destroy(PooledStream pooledStream)    at
    System.Net.ConnectionPool.PutConnection(PooledStream pooledStream, Object owningObject, Int32 creationTimeout, Boolean canReuse)    at
    System.Net.FtpWebRequest.AttemptedRecovery(Exception e)    at
    System.Net.FtpWebRequest.SubmitRequest(Boolean async)
    --- End of inner exception stack trace ---    at
    System.Net.FtpWebRequest.CheckError()    at
    System.Net.FtpWebRequest.GetRequestStream()    at
    ST_0ff7348de65a468bb358ab0206e3721f.ScriptMain.Main() in c:\Users\Stephens\AppData\Local\Temp\Vsta\e664c8a71bb647ff9e9dc6ac32d7b615\ScriptMain.cs:line 155 at 
    System.Net.FtpWebRequest.CheckError()    at
    System.Net.FtpWebRequest.GetRequestStream()    at
    ST_0ff7348de65a468bb358ab0206e3721f.ScriptMain.Main() in c:\Users\Stephens\AppData\Local\Temp\Vsta\e664c8a71bb647ff9e9dc6ac32d7b615\ScriptMain.cs:line 155

由于该错误是如此普遍，因此我决定查看.NET源代码，以了解是否可以了解中断的线索。如果您去这里：

http://labs.developerfusion.co.uk/SourceViewer/browse.aspx?assembly=SSCLI&namespace=System.Net#{%22pageClientState%22%3A%22type-2844%2Ccsharp%22}

并跳至第281行，您将看到内部void PrePush（object ExpectedOwner）的定义，该定义在发生异常时执行。看起来像这样：

    internal void PrePush(object expectedOwner)
    {
        lock (this) {
            //3 // The following tests are retail assertions of things we can't allow to happen.
            if (null == expectedOwner) {
                if (null != m_Owner && null != m_Owner.Target)
                    throw new InternalException();
                // new unpooled object has an owner
            }
            else {
                if (null == m_Owner || m_Owner.Target != expectedOwner)
                    throw new InternalException();
                // unpooled object has incorrect owner
            }

            m_PooledCount++;

            if (1 != m_PooledCount)
                throw new InternalException();
            // pushing object onto stack a second time
            if (null != m_Owner)
                m_Owner.Target = null;
        }
    }

最终，我发现FtpWebRequest仅支持显式FTP（端口21），而不支持隐式FTP（端口990）。明确地在这里指出：

.NET FtpWebRequest是否支持隐式（FTPS）和显式（FTPES）？

无论如何，就我而言，这是一个防火墙问题。最初，我们为隐式FTP配置了端口989、990、49152-65535（根据供应商的技术人员）。我和网络人员核对了一下，然后我们打开了端口20、21、989、990和40000-655535进行了明确显示，之后一切都变得很顺利。

但是，就您而言，似乎似乎有些连接池令人兴奋。这里有关于这个主题的好文章：

如何提高FtpWebRequest的性能？

您可能想看看设置连接池的过程，看看是否可以取得一些进展。希望这可以帮助！

问候，

斯图尔特