We were stuck in an infinite loop inside the rmaps round_robin
component when the user specified a host, then over subscribed it.
Instead of retuning an error, we looped forever.
For example:
$ cat hostfile
A slots=2 max-slots=2
B slots=2 max-slots=2
$ mpirun -np 3 --hostfile hostfile --host B
<hang>
The loop would not terminate because both host A and B are in the
'nodes' structure as they are both allocated to the job. However,
after allocating 2 slots to host B, we remove it from the node list
leaving us with a 'nodes' structure with just A in it. Since we can't
use host A, we keep looping here until we find a node that we can use.
This patch checks to make sure that if we get into this situation where
rmaps is looping over the list a second time without finding a node
during the first pass then we know that there are no nodes left to
use, so we have a resource allocation error, and should return to the user.
This patch should be moved to all of the release branches
This commit was SVN r10131.
2f20a38c98