Comment 8 for bug 1331554

Under Ubuntu, changes in /etc/security/limits.conf only take effect after logging out and back in (or after restarting the system). To increase or remove the limit of number of processes for root user which radosgw runs under, create or adjust in /etc/security/limits.conf.

Set to 2001 in /etc/security/limits.conf, radosgw picks this up:
# grep process /proc/$(pgrep radosgw)/limits
Max processes 2001 unlimited processes

Change to unlimited, log out, log in, then restart radosgw
# sed -i 's/2001/unlimited/' /etc/security/limits.conf
# exit
logout, then log back in
# /etc/init.d/radosgw restart
Starting client.radosgw.gateway...
2014-10-06 18:10:32.871016 7f18e6e1a780 -1 WARNING: libcurl doesn't support curl_multi_wait()
2014-10-06 18:10:32.871022 7f18e6e1a780 -1 WARNING: cross zone / region transfer performance may be affected
/usr/bin/radosgw is running.
# grep process /proc/$(pgrep radosgw)/limits
Max processes unlimited unlimited processes