lsof open files and sockets with users “Too many open files” ulimit -n，#

http://www.tecmint.com/10-lsof-command-examples-in-linux/

http://stackoverflow.com/questions/106234/lsof-survival-guide

http://www.thegeekstuff.com/2012/08/lsof-command-examples/

ulimit -n
Linux でプロセスが開けるファイルディスクリプタの上限
http://stackoverflow.com/questions/9076450/socketexception-too-many-open-files

http://d.hatena.ne.jp/akishin999/20130213/1360711554

一般論
http://stackoverflow.com/questions/13194188/too-many-open-files-when-i-run-a-infinite-socket-open-and-close

Mac
http://stackoverflow.com/questions/880557/socket-accept-too-many-open-files

以下のエラーは要するBにソケット不足でDNSへアクセス出来なかったせいで出る。
#
http://stackoverflow.com/questions/3035226/getaddrinfo-temporary-failure-in-name-resolution-in-ror-application

デーモン等のulimit -n
http://d.hatena.ne.jp/akishin999/20130213/1360711554
https://medium.com/what-i-learned-building/1ef0537ae0e4
http://manpages.ubuntu.com/manpages/dapper/man5/initscript.5.html
http://superuser.com/questions/454465/make-ulimits-work-with-start-stop-daemon
http://stackoverflow.com/questions/21515463/how-to-increase-maximum-file-open-limit-ulimit-in-ubuntu
http://www.xenoclast.org/doc/benchmark/HTTP-benchmarking-HOWTO/node7.html