"open files" with --files --pipe

[Thomas Sattler]

Hi there ...

I tried to use the --pipe and --files options and found
that parallel sometimes stops working. It seems as if
this is somehow related to ulimit's "open files". I
can reproduce it with the following commands:

$ ulimit -n 500; yes | parallel --files --pipe true | nl | tail -n3
   488  /tmp/7T9kEbESkM.par
   489  /tmp/7uqQGUS8r9.par
   490  /tmp/69W44vvzOv.par

$ ulimit -n 400; yes | parallel --files --pipe true | nl | tail -n3
   390  /tmp/5d_P8viQaW.par
   391  /tmp/_NNQspv5Yp.par
   392  /tmp/e54eVHuqNt.par

$ ulimit -n 300; yes | parallel --files --pipe true | nl | tail -n3
   289  /tmp/IUfa7Gzukd.par
   290  /tmp/lu9tP4M0nG.par
   291  /tmp/dA4yMsrkGV.par

The strange thing is, setting the limit to 200 makes
parallel run fine, but pause for a few seconds every
~185 files.

Thomas