[Lazarus] Why does linux+fpc2.2.4+modern lazarus hang? [was: FindInvalidUTF8Character hanging linux hard?]

[Bernd Mueller]

Luca Olivetti wrote:
> En/na Bernd Mueller ha escrit:
> 
>> with "linux hang hard" you mean the machine is completely frozen?
> 
> Yes. I even left it on a text console to see if there was an Oops or 
> something, but it just froze.
> 
>> Does not react on ping and so on?
> 
> Nothing, not even to the magic sysreq key.
> 
>> Could it be a hardware problem?
> 
> I doubt it: it happens on four machines (five if counting my test rig). 
> They're all the same and the problem manifests in all of them since I 
> installed the new version of the program.
> Oh, and I tested on a different machine too (though it's even more 
> underpowered than the epia, but I have that class of machine working 
> reliably with a similar, if not quite the same, kind of program, and 
> with gtk2 and lazarus from around 1 year ago).
> 
>> Maybe the BIOS settings are to "aggressive".
> 
> I tried many different bios settings. Knowing that there's a problem 
> with dma on this board, I even updated the bios. Alas, it made no 
> difference (not that I was expecting one: this system doesn't use 
> neither the disk nor the network).
> 
>> Maybe there is a hardware memory problem, which is only popping up 
>> when you use the modern (perhaps more memory consuming) 
>> fpc/lazarus/gtk environment.
> 
> Memory and cpu consumption is just about the same.
> I used memtest to check for memory errors.
> What's more important, is that the memory usage (VSZ/RSS as reported by 
> ps) of the program is constant once it has reached a plateau value, so 
> apparently it shouldn't be allocating more memory.
> Note that the freeze happens at a random time: it could be 10 minutes, 
> it could be a week (hence, I'm not sure that reverting the development 
> environment actually cured the issue, I need to leave it running for at 
> least a couple of week).

> It always seems to happen doing the same thing though: (i.e., I display 
> various fields on the screen, when reading new data I display dashes in 
> the fields and "Reading" at the bottom of the page, and the crash always 
> happens at that time).

I am no Linux expert, but I think it should be impossible to freeze the 
kernel with a wild running "userland" application. I still think it is 
somehow hardware related.

You could run your application in several virtual machines parallel. May 
be you could use a different Linux distribution/kernel version. The host 
pc (for the hypervisor) should work reliable of course ;-)

Regards, Bernd.