[petsc-dev] PetscIntialize docs

[Satish Balay]

On Thu, 5 Sep 2013, Mark F. Adams wrote:

> 
> On Sep 5, 2013, at 3:29 PM, Satish Balay <balay at mcs.anl.gov> wrote:
> 
> > On Thu, 5 Sep 2013, Mark F. Adams wrote:
> > 
> >> 
> >> On Sep 5, 2013, at 12:46 PM, Satish Balay <balay at mcs.anl.gov> wrote:
> >> 
> >>> On Thu, 5 Sep 2013, Satish Balay wrote:
> >>> 
> >>>> On Thu, 5 Sep 2013, Mark F. Adams wrote:
> >>> 
> >>>>> I wanted to not have files get checked and added -skip_petscrc to
> >>>>> the command line but this was not sufficient.  I needed to change
> >>>>> the code to use NULL (or I told my user to do so).
> >>> 
> >>> Was 'useroptfile' causing some problem - or is it that you wanted to
> >>> avoid it for some other reason?
> >> 
> >> This was the problem with Mira that we went through with Jeff H. last week.  Where getting the home directory was failing occasionally and hanging the system.  So I was told to use -skip_petscrc on the command line, which failed to get the code to skip the (user) RC file.
> > 
> > But did the code hang or crash?
> 
> No, we have been running small problems, for debugging, and small problems to not trigger this bug.


Just to clarify - the buggy 'getpwuid(getuid())' on bgq induced a
deadlock in MPI messaging - which -skip_petscrc avoids. That doesn't
imply 'avoid loading all petscopt/usropt files'.

My fix [with the assumption of 'getpwuid(getuid())' can ocassionally
return null] continues to load the rc files - provided the path can be
resolved.

Jed subsequent change [hasn't merged to maint yet] - is to avoid
getpwuid() - to avoid cases where it can SEGV. [i.e HOME/.petscrc will
never get resolved on bgq]

I haven't seen SEGVs on bgq - but they did occur in preproduction bgq
software stack.

Satish

> 
> > 
> > Satish
> > 
> >> In looking at the code I realized that you need to not give PetscInitialize() an RC file name.   So we need to change the code slightly but it took a while to figure that out (e.g., I had to look at the source).
> >> 
> >>> 
> >>> thanks,
> >>> Satish
> >>> 
> >> 
> >> 
> > 
> 
>