Strange QT application behavior

Question

Hello!

I'm developing a QT application with QTCreator (and QT 4.5.3) on Arch Linux. I'm using KDE 4.3 The project is basically a GUI that let you insert a url and make some web requests to give the user some data back. The web requests are asynchronous.

I've encountered a weird problem. If I start the application the first time and click on the button that launches the web requests, it crashes. On the second time it works as expected. The third and the fourth time it returns just one of the 900 values I was expecting.

What's strange is that on Windows (and QT 4.6) is working always fine.. Have you ever seen such a thing? Thanks in advance for your information

Best regards

Answer 1

I'd say that has something to do with cookies.

Try to create the smallest possible application that reproduces that bug and then try to determine, if it's your or Trolltech's code that crashes.

Answer 2

I've never seen anything exactly like this, but I have seen different behaviours between Linux and Windows where the Windows code seemed to work. In my experience, the code is almost always wrong - it's just much easier to catch it when you run in Linux.

I have two suggestions to make:

• run with Valgrind: this will catch the obvious flaws
• link with the Qt debug libs (usually QtCored.so, QtGuid.so on Linux)

And a third: look very carefully at the web requests responses in Linux / Windows, possibly in a diff-scanner. Any differences might point you in the right direction