simplified tests to try to isolate parse issue
this fails 100%
python test_50_nongz_fvec.py -cj ../testdir_hosts/pytest_config-163.json
or
ssh onto 163 and execute in your local h2o tree (git/build)
python test_50_nongz_fvec.py
 ERRR WATER: Missing vector during Frame fetch: $04ff00000000ffffffff$nfs://home/0xdiag/home-0xdiag-datasets/manyfiles-nflx/file_139.dat
[2014-05-20 00:34:02.129368] java.lang.NullPointerException
[2014-05-20 00:34:02.129506]     at water.fvec.Frame$1.compute2(Frame.java:151)

got it down to just 2 jvms. use 40GB heap but smaller probably is ok (it fails right away..not much parsing)