setting distinct core file names

[Konstantin Belousov]

On Wed, Nov 28, 2018 at 12:21:33PM +0100, Willem Jan Withagen wrote:
> On 28-11-2018 11:43, Willem Jan Withagen wrote:
> > On 27-11-2018 21:46, Conrad Meyer wrote:
> >> One (ugly) trick is to use multiple filesystem links to the script
> >> interpreter, where the link names distinguish the scripts.  E.g.,
> >>
> >> $ ln /bin/sh /libexec/my_script_one_sh
> >> $ ln /bin/sh /libexec/my_script_two_sh
> >> $ cat myscript1.sh
> >> #!/libexec/my_script_one_sh
> >> ...
> >>
> >> Cores will be dumped with %N of "my_script_one_sh."
> > 
> > Neat trick... got to try and remember this.
> > But it is not the shell scripts that are crashing...
> > 
> > When running Ceph tests during Jenkins building some 
> > programs/executables intentionally crash leaving cores.
> > Others (scripts) use some of these programs with correct input and 
> > should NOT crash. And test during startup and termination that there are 
> > no cores left.
> > 
> > One jenkins test run takes about 4 hours when not executed in parallel. 
> > I'm testing 4 version multiple times a day to not have this huge list of 
> > PRs the go thru when testing fails.
> > 
> > But the intentional cores and the failure cores here collide.
> > And when I have a core program_x.core I can't tell if they are from a 
> > failure or from an intentional crash.
> > 
> > Now if could tell per program  how to name its core that would allow me 
> > to fix the problem, without overturning the complete Ceph testing 
> > infrastructure and still keep parallel tests.
> > 
> > It would also help in that "regular" cores just keep going the way the 
> > are. So other application still have the same behaviour. And are still 
> > picked up by periodic processing.
> 
> So I read a bit more about the prcctl and prctl(the Linux variant) and 
> turns out that Linux can set PR_SET_DUMPABLE. And that is actually used 
> in some of the Ceph applications...
> 
> Being able to set this to 0 or 1  would perhaps be a nice start as well.
Isn't setrlimit(RLIMIT_CORE, 0) enough ?  It is slightly different syntax,
but the idea is that you set RLIMIT_CORE to zero, then we do not even
start dumping.