MPICH2 gethostbyname failed

Question

I don't understand the error message. I am trying to do is to run a MPICH2 application after I installed mpich2 version 1.4 or 1.5 to /opt/mpich2 (both version failed with the same error). My MPI application was compiled with 1.3 but I am able to run it with mpi 1.4 on another workstation. I am testing it on Ubuntu 12.04.

Fatal error in PMPI_Init_thread: Other MPI error, error stack:
MPIR_Init_thread(467)..............: 
MPID_Init(177).....................: channel initialization failed
MPIDI_CH3_Init(70).................: 
MPID_nem_init(319).................: 
MPID_nem_tcp_init(171).............: 
MPID_nem_tcp_get_business_card(418): 
MPID_nem_tcp_init(377).............: gethostbyname failed, localhost (errno 3)

Answer 1

Solution for macOS

I stumbled upon this issue on macOS 10.12.1.

The solution is to add 127.0.0.1 computername.local to /etc/hosts. Your file will look more or less like this:

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##
127.0.0.1   localhost
127.0.0.1   computername.local
255.255.255.255 broadcasthost
::1             localhost 

You can change/check your computer's name if you go to System Preferences > Sharing > Computer Name.

Answer 2

What worked for me was the following:

Make sure your hostname is the same for 1 and 2 below:

1. terminal hostname
2. "/etc/hosts" hostname

So if you type cat /etc/hosts in terminal it should look like:

// 127.0.0.1       my_hostname

My hostname was not the same for 1 and 2 for me. Once I changed them to match then my mpi program would execute.

To change your terminal hostname type the following: sudo scutil --set HostName my_new_host_name

To change your /etc/hosts hostname type the following: sudo nano /etc/hosts

and then add the line

127.0.0.1       my_new_hostname

Answer 3

This error indicates that there's a problem resolving localhost. Check your /etc/hosts file, make certain that you have localhost correctly defined here, it should be pointing to 127.0.0.1. Try using ssh to connect to localhost, make sure that works as well.

Answer 4

Being the question different, the answer is probably the same I gave time ago for OpenMPI: gethostname() function missing in openMPI

The MPI portable solution is to use MPI_Get_processor_name()

Answer 5

Maybe your /dev/shm is full, try to clean it.