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SFTP client double callback from OnOpenFile

Posted: 05/08/2012 03:49:15
by Keith Fowler (Standard support level)
Joined: 05/08/2012
Posts: 3

Using the TElSftpClient class (version 8) in a production environment, going against a UNIX SFTP server, we occasionally get a double callback from the OnOpenFile event.

I have sufficient logging from the server side to be fairly sure that the open file response is not being sent twice. I have also ruled out double subscription for the event or similar problem in our client code.

Are there any circumstances in which this has been observed before, or are there any in which it might happen?
Posted: 05/08/2012 04:05:59
by Ken Ivanov (Team)

Thank you for contacting us.

Could you please assign the licence ticket you received in the registration letter to your web site account so that we could identify you as a customer? This will particularly let us know about the SecureBlackbox edition you are using, what is important for problem investigation.

I definitely can say that we didn't come across any similar issues before. Are both event calls totally identical (with respect to parameter values and call stacks)?
Posted: 05/08/2012 04:59:00
by Keith Fowler (Standard support level)
Joined: 05/08/2012
Posts: 3

I have linked the licence ticket.

We are using version 8 of the .NET DLLs.

We have some problems with diagnosis because the problem occurs very infrequently and at a customer's site, so I don't have a call stack.
Posted: 05/08/2012 05:37:31
by Ken Ivanov (Team)

Thank you for the details.

Let's try to localize the issue. May I please ask you to answer the following questions:

1. In what scenario does the issue occur? I.e., does it happen with the very first call to OpenFile() within a particular session, or with one of subsequent calls? Did you notice whether the problematic OpenFile() calls are always preceded by a specific sequence of other requests (e.g. directory listing requests, rename/delete requests etc.)?

2. Does the problem always occur with the same SFTP server or with different servers?

3. Do you use brand new TElSFTPClient and TElSSHClient objects for every new session? If you don't, it makes sense to try to re-design the application so that new SSH/SFTP objects were used for every new session the application opens.

It is desirable that you add an extra logging to your application so that we could get more information about the problem. In particular, it is really important to know
- the name of the server-side SSH/SFTP software (TElSSHClient.ServerSoftwareName),
- whether both OnOpenFile calls are made with the same values of the Handle parameters and call stacks.
Posted: 05/08/2012 09:14:32
by Keith Fowler (Standard support level)
Joined: 05/08/2012
Posts: 3

I now have a bit more to go on that suggests I have a race condition, so I need to look into that further. Sorry for the trouble. You can close the issue now.



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