I'm currently developing a .net windows service which is supposed to manage a number of FTP-connections to different FTP-servers. I am using the Xceed.Ftp.FtpClient for sending and receiving files and i am very pleased with the features in the xceed components. However i am having problems with increasing memusage over time. When the service has been running for exampel for 2 weeks and i look in the taskmanager it is allocating over 200 000 kB. After a number of different test to locate this memory leakage i now suspect the Xceed.Ftp.FtpClient. During an upload / download of a file the memusage increases in the program but it never seems to go down again.

Even if i run the simple example from below i have the same problem with increasing memory usage.


I am using VS2008 and the target framework is .net 2.0

Does anyone have a tip for me to get rid of this problem?

Best regards Fredrik Lindros

///////////////////////////////////////////////////////////////////////
Xceed.Ftp.Licenser.LicenseKey = "XXXX-XXXX-XXXX-XXXX";
Xceed.Ftp.FtpClient ftp = new Xceed.Ftp.FtpClient();

ftp.Connect("HOSTNAME", 21);
ftp.Login("USERNAME", "PASSWORD");
ftp.ChangeCurrentFolder("FOLDER");

System.IO.FileStream filestream;

for (int i = 0; i < 100; i++)
{
filestream = new System.IO.FileStream(@"c:\temp\PDF.pdf", System.IO.FileMode.Create);
ftp.ReceiveFile("PDF.pdf", filestream);
filestream.Flush();
filestream.Close();
filestream.Dispose();

}

ftp.Disconnect();

ftp = null;
///////////////////////////////////////////////////////////////////////

We fixed a memory leak bug in the <a href="http://download3.xceedsoft.com/Packages/3.2.7614.12380/XceedComponents.exe">last version</a> of the component.

However, if this does not fix your issue, contact us directly at <a href="mailto:support@xceedsoft.com">support</a> and we will investigate further.

---

Charles Bérubé-Rémillard
Technical Support
Xceed Software Inc.

Using SOS to analyse the library using your sample code and a ±2Mb file, there is effectivly a rising memory usage. This is caused by the fact that you dispose the stream used to transfer data, but some internal objects just don't have time to be garbage collected.

You can see the difference by calling GC.Collect() inside your for() loop.

You can also check the memory using SOS extention. Here is the result before and after calling GC.Collect() just before setting the FtpClient variable to null:

// Memory analysis before calling Garbage Collector
!load sos
extension C:\Windows\Microsoft.NET\Framework\v2.0.50727\sos.dll loaded
!dumpheap -stat -type Xceed
PDB symbol for mscorwks.dll not loaded
total 820 objects
Statistics:
MT Count TotalSize Class Name
01401844 1 12 Xceed.Ftp.Engine.FtpTracing
0140178c 1 12 Xceed.Ftp.FtpVmsListingParser
014016ec 1 12 Xceed.Ftp.FtpAS400ListingParser
01401650 1 12 Xceed.Ftp.FtpUnixListingParser
014015c8 1 12 Xceed.Ftp.FtpDosListingParser
014053e4 1 20 Xceed.Ftp.Engine.FtpCommandChannel+AsyncReceiveState
0140cefc 1 28 Xceed.FileSystem.EmptyFileSystemEvents
01402cb4 1 28 Xceed.Ftp.Engine.FtpDataFormat
01400e04 1 28 Xceed.Ftp.FtpListingParserList
014029fc 1 32 Xceed.Ftp.ParsingListingLineEventHandler
0140290c 1 32 Xceed.Ftp.CertificateRequiredEventHandler
0140281c 1 32 Xceed.Ftp.CertificateReceivedEventHandler
0140272c 1 32 Xceed.Ftp.ReplyReceivedEventHandler
0140263c 1 32 Xceed.Ftp.CommandSentEventHandler
00129f64 1 32 Xceed.Compression.Formats.CompressionFormatsLicense
00128eac 1 32 Xceed.Compression.CompressionLicense
001281ec 1 32 Xceed.FileSystem.FileSystemLicense
00126884 1 32 Xceed.Ftp.FtpLicense
01400ffc 1 44 Xceed.Ftp.Engine.FtpEngine
01403da4 2 64 Xceed.Utils.Security.Ssl.CertVerifyEventHandler
01403cb4 2 64 Xceed.Utils.Security.Ssl.CertRequestEventHandler
014013fc 1 92 Xceed.Ftp.Engine.FtpCommandChannel
00124aa4 1 108 Xceed.Ftp.FtpClient
0140a3a4 12 192 Xceed.Ftp.TransferringFileEventArgs
0140dd74 13 260 Xceed.Ftp.Engine.FtpDataConsumerCommand+CopyStreamState
01402b44 24 288 Xceed.Ftp.RepresentationTypeOption
0012487c 24 288 Xceed.Ftp.RepresentationType
0140c8f0 13 364 Xceed.Ftp.Engine.ProgressionEventArgs
0140d96c 13 416 Xceed.Utils.Streams.ClosingStreamEventHandler
01405234 13 416 Xceed.Utils.Security.Ssl.AsyncResult
014082fc 36 432 Xceed.Ftp.CommandSentEventArgs
0140d824 13 520 Xceed.Utils.Streams.MemoryHandlerStream
0140a534 13 520 Xceed.Utils.Security.Ssl.SecureNetworkStream
01409a1c 13 572 Xceed.FileSystem.SingleFileFolder
014057ec 50 600 Xceed.Ftp.ReplyReceivedEventArgs
01408c0c 32 640 Xceed.Ftp.Engine.PassiveFtpDataChannel
014084ec 13 728 Xceed.Ftp.Engine.TypeFtpCommand
01409544 13 780 Xceed.FileSystem.StreamFile
01408afc 13 780 Xceed.Ftp.Engine.PassiveFtpCommand
0140a2d4 26 832 Xceed.Ftp.Engine.ProgressionEventHandler
0140a1e4 26 832 Xceed.Ftp.TransferringFileEventHandler
0140a0f4 26 832 Xceed.Ftp.FileTransferStatusEventHandler
0140d0e4 13 884 Xceed.FileSystem.FileSystemEventsSession
0140884c 13 1040 Xceed.Ftp.Engine.ReceiveFileFtpCommandSequence
01403264 33 1188 Xceed.Utils.Security.Ssl.SecureSocket
014056a4 52 1248 Xceed.Ftp.StringList
01403be4 52 1248 Xceed.Ftp.FtpReply
01409ecc 13 1300 Xceed.Ftp.FileTransferStatusEventArgs
014086a4 13 1508 Xceed.Ftp.Engine.RetrieveFileFtpCommand
01409c24 32 1664 Xceed.Utils.Streams.WindowStream
0140469c 50 2000 Xceed.Ftp.Engine.FtpCommandAsyncResult
0140389c 60 2640 Xceed.Utils.Security.Ssl.SecurityOptions
014045d4 78 3120 Xceed.Ftp.Engine.FtpAsyncResult
Total 820 objects


// Force Garbage Collection
GC.Collect()


// Memory Analysis just after
Expression has been evaluated and has no value
!dumpheap -stat -type Xceed
total 81 objects
Statistics:
MT Count TotalSize Class Name
01401844 1 12 Xceed.Ftp.Engine.FtpTracing
0140178c 1 12 Xceed.Ftp.FtpVmsListingParser
014016ec 1 12 Xceed.Ftp.FtpAS400ListingParser
01401650 1 12 Xceed.Ftp.FtpUnixListingParser
014015c8 1 12 Xceed.Ftp.FtpDosListingParser
014053e4 1 20 Xceed.Ftp.Engine.FtpCommandChannel+AsyncReceiveState
0140cefc 1 28 Xceed.FileSystem.EmptyFileSystemEvents
01402cb4 1 28 Xceed.Ftp.Engine.FtpDataFormat
01400e04 1 28 Xceed.Ftp.FtpListingParserList
014029fc 1 32 Xceed.Ftp.ParsingListingLineEventHandler
0140290c 1 32 Xceed.Ftp.CertificateRequiredEventHandler
0140281c 1 32 Xceed.Ftp.CertificateReceivedEventHandler
0140272c 1 32 Xceed.Ftp.ReplyReceivedEventHandler
0140263c 1 32 Xceed.Ftp.CommandSentEventHandler
00129f64 1 32 Xceed.Compression.Formats.CompressionFormatsLicense
00128eac 1 32 Xceed.Compression.CompressionLicense
001281ec 1 32 Xceed.FileSystem.FileSystemLicense
00126884 1 32 Xceed.Ftp.FtpLicense
01400ffc 1 44 Xceed.Ftp.Engine.FtpEngine
01403da4 2 64 Xceed.Utils.Security.Ssl.CertVerifyEventHandler
01403cb4 2 64 Xceed.Utils.Security.Ssl.CertRequestEventHandler
014013fc 1 92 Xceed.Ftp.Engine.FtpCommandChannel
00124aa4 1 108 Xceed.Ftp.FtpClient
01408c0c 13 260 Xceed.Ftp.Engine.PassiveFtpDataChannel
01403264 14 504 Xceed.Utils.Security.Ssl.SecureSocket
01409c24 13 676 Xceed.Utils.Streams.WindowStream
0140389c 16 704 Xceed.Utils.Security.Ssl.SecurityOptions
Total 81 objects

if you use !gcroot to check what is using those references, you get something like this:

Scan Thread 7988 OSTHread 1f

---

André
Software Developer and Tech Support
Xceed Software Inc.

Thanks. Everything is working fine now after i upgraded to the latest version of the library

Regards Fredrik