[petsc-users] Is PETSc using internet?

[Satish Balay]

On Tue, 21 Jul 2020, Lawrence Mitchell wrote:

> 
> 
> > On 21 Jul 2020, at 10:49, Eda Oktay <eda.oktay at metu.edu.tr> wrote:
> > 
> > Hi all,
> > 
> > I am using the following libraries and for some reason, I figured out
> > that if ı am disconnected to internet, my program is not working:
> 
> [...]
> 
> > I thought that there is no reason for PETSc to go online for libraries
> > but I couldn't find any other reason.
> > 
> > The first thing I am doing in my program after initializing SLEPc and
> > PETSc is reading the binary matrix from my file and when I am offline,
> > the program can't even get the matrix.
> 
> My crystal ball (which sometimes is wrong) guess that you're using a Mac, and MPICH as your MPI version? If so, it may be a problem in MPI_Init failing to resolve localhost to an IP address.
> 
> If these guesses are correct, does it help to add
> 
> 127.0.0.1       LOCALHOSTNAME.local
> 127.0.0.1       LOCALHOSTNAME
> 
> to /etc/hosts
> 
> where LOCALHOSTNAME is the name of the machine (as reported by hostname)

The equivalent command is:

echo 127.0.0.1 `hostname` | sudo tee -a /etc/hosts

Satish