max processes change in RHEL6/SL6
There have been a log configuration file layout changes since RHEL6, but you might not noticed that there is hiden change for regular user -- max processes lowered to 1024.
# cat /etc/security/limits.d/90-nproc.conf
# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.
* soft nproc 1024
root soft nproc unlimited
change the configuration file for particular user to proper value to avoid 'Out of Memory' fault.
Here is the different between regular user and root user(number vary on different machines)
$ ulimit -u
# ulimit -u