[Qt-interest] system crash when using external dll

[Thiago Macieira]

On Wednesday, 21 de September de 2011 09.46.52, Vincent Cai wrote:
> Could anybody give me some hints, so that I can try something to continue my
> works. :)
>  Any reference document or any debug method is welcome.
> 
> I Love Qt!

We can't help you because you haven't posted nearly enough information for us 
to start.

When people come with this vague information on IRC, my recommendation is that 
they follow these steps:

1) find the bug
2) fix it

If you'd rather, I can expand and say:

1) hypothesise what the cause of the bug is
2) create a test to prove or disprove if that is the cause (one such test is 
to try and fix what you think the problem is)
3) execute the test
4) if it fails, go back to 1

For problems related to crashes, I also recommend the following sources of 
information:

a) the backtrace of the crash and verify the validity of every single pointer 
used in the line that caused the crash

b) the valgrind log of the application.

Note that I recommend valgrind even for people developing on Windows. If your 
code is cross-platform, use Linux. It's worth to have a Linux system even if 
the only thing you need it for is valgrind. If you have non-cross-platform 
code, you can buy similar tools from IBM (Purify) or you can try Intel's 
Parallel Studio XE, which also contains a memory debugger (it's free for non-
commercial use).

If all else fails, start reducing the code to the minimum necessary to 
reproduce the crash. One of two outcomes are possible out of this: either 
you'll find the issue in the process, or you'll end up with a very small 
testcase, which you can share with others to try and get help. Your objective 
is 200 lines of self-contained code.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
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