Duplicate requests with FiddlerCore

6 posts, 0 answers
  1. Shab
    Shab avatar
    2 posts
    Member since:
    Feb 2014

    Posted 13 Feb 2014 Link to this post

    We are using FiddlerCore (v. 4.4.5.6) to capture traffic from our test suite that makes calls against the product servers (behind a VIP). And we are finding ghost requests hitting our servers - that is:
    1. The Fiddler log from the client (saved using FiddlerCore) shows a single call.
    2. The server logs from product servers shows that two different servers handled this same request.
    The request has a unique  randomly generated secret token, so we know that it is the exact same request. So somehow a duplicate request is being fired that does not show up in the FiddlerCore trace. We discounted for now a potential issue with the F5-VIP for now.

    This issue repros intermittently - so we can't really validate by just disabling FiddlerCore integration.

    Is it possible for us to introduce such a scenario if we have a bug in how we integrate with the FiddlerCore session callbacks?

    Or is there a possible bug in the version of FiddlerCore that we are using that might result in this behavior?

    Appreciate any pointers,
    Thanks!
  2. EricLaw
    EricLaw avatar
    67 posts
    Member since:
    Oct 2012

    Posted 13 Feb 2014 in reply to Shab Link to this post

    Do you see the same behavior if you use Fiddler? Do you have a network capture (e.g. Wireshark)?

    If your server is using KeepAlive connections AND Fiddler reuses a connection AND the server fails to accept a request on that reused connection (e.g. by closing the connection) then Fiddler will resend the request on another (or new) connection. In practice, servers rarely accept requests without replying to them, but if there were a bug in the server, it's conceivable that this could occur.
  3. Shab
    Shab avatar
    2 posts
    Member since:
    Feb 2014

    Posted 14 Feb 2014 in reply to EricLaw Link to this post

    I am working on getting a repro with NetMon tracing enabled. Will update this thread once I get more data.
  4. Russell
    Russell avatar
    2 posts
    Member since:
    Feb 2014

    Posted 27 Feb 2014 Link to this post

    Hi Eric, Shab and I have collected NetMon and Fiddler tracing for this situation.  Can you please contact me offline so that I can share this information with you?
  5. EricLaw
    EricLaw avatar
    67 posts
    Member since:
    Oct 2012

    Posted 27 Feb 2014 in reply to Russell Link to this post

    I'm not sure how I'd contact you offline. If you'd like to email me, Help > Send Feedback in Fiddler, or mail fiddler@telerik.
  6. Russell
    Russell avatar
    2 posts
    Member since:
    Feb 2014

    Posted 27 Feb 2014 in reply to EricLaw Link to this post

    Thanks I'll contact you at that email.
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