ubuntu-phone team mailing list archive

[Robert Schroll <rschroll@xxxxxxxxx>]

Hi all,

I've got a Sunday afternoon / evening / night / 
I-live-in-Asia-you-insensitive-clod puzzler for you.

I've been working on the ebook reader Beru, and I've been getting 
crashes on start about 50% of the time.  I'd been hoping that this was 
just related to launching from Qt Creator.  But I tried installing it 
and still got crashes about half the time I launched it.

So, I dug out the instructions for running under gdb, got a crash, and 
discovered the stack had been corrupted.  Poor little Python-loving me 
didn't even know that this was a thing that could happen!

I bisected to find the problem commit, and discovered that it was when 
I added sections to the first page in my page stack.  Obviously this 
couldn't be the problem, but I removed the sections just to check.  And 
the crash went away.

Once I saw that, it was obvious that the problem was in my handler for 
changing the selected section.  So I removed the handler (making the 
sections affect nothing), and the crash remained!

To try to separate the crash from the general hubbub of initialization, 
I removed the sections from the Page head, and set them procedurally 
after everything was loaded.  Obviously, this wouldn't make a 
difference.  But it stopped the crashes.

So far, I'm batting 0-for-3 on this one.  So I'd like to hear if any of 
you have an idea what's going on.  For now, delaying setting the 
sections is working, but I have a feeling that I'm jut hiding a bug.  
I'd like to find and fix it, or at least assure myself that this is a 
sensible work-around.

I haven't managed to come up with a simple test case yet.  A basic 
page-with-sections test works just fine, so it has something to do with 
all the other things going on.  Here's the problematic commit [1], the 
solution commit [2], and a bug report with some more info [3].  You're 
welcome to reply to the bug if you'd rather not do this over the list.

Thanks,
Robert

[1] 
https://github.com/rschroll/beru/commit/9f8a299d0ecc5c6454e0b2b5d8f54a883b4b3328
[2] 
https://github.com/rschroll/beru/commit/4d521b66e83596ce2a6cb9587e523bae1db0a1d4
[3] https://github.com/rschroll/beru/issues/82