title: Gnu Parallel : nested parallelism
body: <p>Is it possible to call gnu parallel from within multiple runs of a script that are in-turn spawned by gnu parallel? </p>
  
  <p>I have a python script that runs for 100s of <strong>sequential</strong> iterations,  and somewhere within each iteration, 4 values are being computed in parallel (using gnu parallel). Now I want to spawn multiple such scripts at the same time, again, using gnu parallel. Is this possible? Will gnu parallel take care of good utilization of available cores? </p>
  
  <p>For example, if in the inner loop, out of 4 values, 2 have been completed and 2 are running, so that a single script cannot proceed to the next iteration until all 4 values are computed.  Will the two free cores be used for computing results for a different run of the script automatically?
  How can I specify the total number of cores available? In the inner call to parallel or outer call?</p>
  
  <p><a href="https://stackoverflow.com/questions/23411266/calling-gnu-parallel-from-gnu-parallel">This</a> questions shows it is possible to nest calls to parallel, but I'm not sure if this changes when I'm calling the nested parallel from inside a script.</p>
  
  <p>PS: Thrashing is not a concern, I can use a LOT of cores from a large cluster.</p>
  
  <p>PS2: gnu-parallel is an AWESOME tool... thanks! : )</p>