How to use parallel on multiple computer to have a list of tasks done only once?

Question

I am trying to use parallel on multiple server using ssh, what actually I would like to do is something like:

    parallel -s computer_list.txt < command.txt

where in server_list.txt there is list of server and in command.txt looks like

    fist_job.sh
    second_job.sh
    ...

But I don't want that all the server do all the jobs in the list, I want that each *.sh is executed just one time on a random server, all of them can reach all files that they need to execute each command.

In other words what I am looking for is a kind of generalization of:

   parallel < command.txt

Answer 1

I guess you could do something like this:

servers.txt

server1
server2
server3
server4
serverA
serverB
raspi10
raspi11
raspi12
raspi13
supercomputerA
supercomputerB

jobs.txt

job1
job2
job3
job4
job5
job6

Then use this bash script:

#!/bin/bash

# Read in list of jobs into array
jobs=( $(<jobs.txt) )

# Get randomised list of servers
servers=( $( gshuf servers.txt) )

# Assign each job to a server and execute in parallel
for ((i==0;i<${#jobs[@]};i++)) ; do
   echo "ssh \"${servers[i]}\" \"${jobs[i]}\""
done | parallel

Example

That generates the following input for GNU Parallel:

ssh "raspi12" "job1"
ssh "serverA" "job2"
ssh "serverB" "job3"
ssh "raspi13" "job4"
ssh "server3" "job5"
ssh "supercomputerB" "job6"

---

Notes:

gshuf is how GNU shuf (shuffle) is installed on a Mac. It may be known as shuf on other machines.

Answer 2

This works for me:

parallel --slf computer_list.txt < command.txt

I use version 20180822.