[petsc-users] Is PETSc using internet?

[Lawrence Mitchell]

> 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)

Lawrence