tile-join too many files?

[hfu]

31ms for AdmArea
35ms for Cstline
124ms for WA
rake aborted!
Command failed with status (101): [parallel --line-buffer ' ogr2ogr -lco RS=Y...]
/home/pi/fgd/stream.rb:60:in `produce'
/home/pi/fgd/Rakefile:28:in `block in <top (required)>'                        
Tasks: TOP => produce
(See full trace by running task with --trace)                                  

real    255m14.179s
user    839m40.931s
sys     103m38.410s