Checkpoints files missing when some ranks not assigned

[kpgriesser]

1 - Detailed description of problem or enhancement

While testing combinations of ranks and threads, checkpoints files are not generated in some cases.

2 - Describe how to reproduce the issue

Test case is a 2 component system that simulates for 10 us.
Using --checkpoint-sim-period=1us we see checkpoints generated as expected for these cases:

• 1 rank, 1 thread
• 1 rank, 2 threads
• 1 rank, 3 threads
• 2 ranks, 1 thread

However, when we use 2 ranks, 2 threads we see no checkpoint files at all along with the warning message 'no components assigned to rank 1.0 and 1.1'.

As a side request, there appears to be 1 simulation checkpoint log message for each thread. For 3 threads, for example: # Simulation Checkpoint: Simulated Time 9 us (Real CPU time since last checkpoint 0.01255 seconds)
# Simulation Checkpoint: Simulated Time 9 us (Real CPU time since last checkpoint 0.01257 seconds)
# Simulation Checkpoint: Simulated Time 9 us (Real CPU time since last checkpoint 0.01260 seconds)
# Simulation Checkpoint: Simulated Time 10 us (Real CPU time since last checkpoint 0.01275 seconds)
# Simulation Checkpoint: Simulated Time 10 us (Real CPU time since last checkpoint 0.01278 seconds)
# Simulation Checkpoint: Simulated Time 10 us (Real CPU time since last checkpoint 0.01288 seconds)

However, there is only 1 log message per rank when using multiple ranks. I would be helpful to reduce the log file size by only producing 1 message per checkpoint regardless of the number of threads and ranks.

3 - What Operating system(s) and versions
All

4 - What versions of external libraries (MPI, etc.)
mpirun (Open MPI) 4.1.2

5 - Provide sha1 of all relevant SST repositories (sst-core, sst-elements, etc)
sst-core