title: How to stop parallel from reporting "No more processes" with "-X" option?
body: <p>Working off this example: <a href="http://www.gnu.org/software/parallel/man.html#EXAMPLE:-Speeding-up-fast-jobs" rel="nofollow">http://www.gnu.org/software/parallel/man.html#EXAMPLE:-Speeding-up-fast-jobs</a></p>
  
  <p>When I run:</p>
  
  <pre><code>seq -w 0 9999 | parallel touch pict{}.jpg
  seq -w 0 9999 | parallel -X touch pict{}.jpg
  </code></pre>
  
  <p>Success! However, add another 9 and BOOM:</p>
  
  <p><code>$ seq -w 0 99999 | parallel --eta  -X touch pict{}.jpg
  parallel: Warning: No more processes: Decreasing number of running jobs to 3. Raising ulimit -u or /etc/security/limits.conf may help.
  Computers / CPU cores / Max jobs to run
  1:local / 4 / 3
  parallel: Warning: No more processes: Decreasing number of running jobs to 2. Raising ulimit -u or /etc/security/limits.conf may help.
  parallel: Warning: No more processes: Decreasing number of running jobs to 1. Raising ulimit -u or /etc/security/limits.conf may help.
  parallel: Error: No more processes: cannot run a single job. Something is wrong.
  </code></p>
  
  <p>I would expect <code>parallel -X</code> to run no more jobs than I have cpu cores, and to cram as many parameters onto each job as the max command line length permits. How am I running out of processes?</p>
  
  <p>My environment:</p>
  
  <ul>
  <li>OSX Yosemite</li>
  <li><code>ulimit -u</code> == 709</li>
  <li>GNU parallel 20141122</li>
  <li>GNU bash, version 3.2.53(1)-release (x86_64-apple-darwin14)</li>
  </ul>