Why does my Perl script exit with 137?
137=128+9, which means some other process has sent you a signal 9, which is SIGKILL. I.e. the other script kills yours, that's what it looks like.
I just ran into the same exit code 137 when launching a python script. It turns out to be the OOM killer kicking in, sending SIGKILL to python interpreter. If it's the same cause, you can find oom msgs in /var/log/messages