Random Notes on Scaling

parallel-ssh has a -I option to feed in a shell script file such that quotes escaping is not needed. On Ubuntu 14.04, the HAProxy may have 2 pids after sudo service haproxy restart. I suspect one of them is a zombie since the new open file limit does not apply. The safer way is to killall haproxy then sudo service haproxy start. HAProxy has a maxconn globally and maxconn for each frontend.