Avoiding LibreOffice DOS

[MJ]

On 18/10/2019 11:31 pm, Andrea Venturoli wrote:
> On 2019-10-17 23:59, MJ wrote:
>
>>> As I said, I think it's a problem with memory.
>>
>> Oh did you? I saw you mention "vmemoryuse" but didn't understand whether you meant this was the cause or just an attempt to fix one cause.
>
> Sorry, maybe I should have made this clearer.
>
Yes, because I was under the impression this was about debugging a user program. It's no problem, just took a while to get to your specific issue.
>
>
>> If it is memory related, perhaps you need to create a larger swap space. It might just get you over the hump of exhausting memory enough for Libreoffice to complete whatever it is it's trying to do.
>
> My guess is that it will use as much as it's available.
>
Of course, but if your goal was to debug the problem, this may have given you more time to trace it using dtrace or truss or your tool of choice.


>
>
>> Conjecture? There's a tight loop. Possibly/likely a bug in libreoffice? 
>
> Possibly, but, as I said, I'm trying to approach this from an OS perspective as a general case.
> This time it was LibreOffice, but I was also able to reproduce this with different applications (e.g. remove swap, fire up a couple of VirtualBox VMs to eat most memory, open several pages in FireFox).
>
>

So, what you're effectively attempting to achieve is debugging the kernel and how it handles memory reclamation/caching etc. In this case, you need to concentrate on not per-user but system wide.

You need to begin to learn and experiment with things like vm.v_free_/*/  and all the various tweaks while using vmstat.

In the extreme, you may need to look at setrlimit(2) and writing a test harness around a rogue memory-using program (I'm not sure of your level - if any - of programming knowledge).


Apart from all that, it's just going to be you experimenting, setting limits, trying, re-trying etc. In which case, you would be mad not to do this in a virtual environment as I suggested.


Regards

Mark