Running multiple sets in loop intermittently causes graphics device to stop working.

[jmelott]

Running the following script failed once when trying to run for 5 sets across 5 different numbers of processors. The failure was that it could not start the graphics device for another set. This happened between sets rather than in the middle of one. Note: This is not a normal use case for RPPASPACE. Modifying the script to finish the sets/processors after where it failed and restarting R seemed to suffice to get past the error.

RPPASPACE_timing_test_with_combined_png_output.R.txt