Hi, I want to ask, if it is really needed to use ulimit or /etc/security/limits.conf to increase max_filedescriptors value? From my testing, it seems not.
*= my environment:* CentOS 6.9 Squid 3.1.23 / 3.4.14 *- default ulimits for root and other users:* [root@...]# ulimit -Sa | grep -- '-n' open files (-n) 1024 [root@...]# ulimit -Ha | grep -- '-n' open files (-n) 4096 *- default ulimits for squid user:* [root@...]# sudo -u squid /bin/bash bash-4.1$ id uid=23(squid) gid=23(squid) groups=23(squid),... bash-4.1$ ulimit -Sa | grep -- '-n' open files (-n) 1024 bash-4.1$ ulimit -Ha | grep -- '-n' open files (-n) 4096 *- processes:* [root@...]# ps aux | grep squid root 7194 0.0 0.1 73524 3492 ? Ss May17 0:00 squid -f /etc/squid/squid.conf squid 7197 0.2 10.9 276080 210156 ? S May17 4:53 (squid) -f /etc/squid/squid.conf squid 7198 0.0 0.0 20080 1084 ? S May17 0:00 (unlinkd) *- error and warning messages from cache.log:* client_side.cc(3070) okToAccept: WARNING! Your cache is running out of filedescriptors comm_open: socket failure: (24) Too many open files IpIntercept.cc(137) NetfilterInterception: NF getsockopt(SO_ORIGINAL_DST) failed on FD 68: (2) No such file or directory ... (many with different FD) I found many How-tos like these - https://access.redhat.com/solutions/63027 and https://www.cyberciti.biz/faq/squid-proxy-server-running-out-filedescriptors/. Both how-tos mention editing the file /etc/security/limits.conf and adding the line "* - nofile 4096" to increase the nofile limit for all users except root - I don't like this. According to my test, see below, this is not necessary, but I want to be sure, so I'm writing here. *a) Squid default configuration (max_filedesc 0) and default nofile limit (1024/4096):* [root@...]# ps aux | grep squid root 17837 0.0 0.1 73524 3496 ? Ss 13:45 0:00 squid -f /etc/squid/squid.conf squid 17840 0.3 0.5 76552 10860 ? S 13:45 0:00 (squid) -f /etc/squid/squid.conf squid 17841 0.0 0.0 20080 1084 ? S 13:45 0:00 (unlinkd) [root@...]# grep -E "Limit|Max open files" /proc/17837/limits Limit Soft Limit Hard Limit Units Max open files 1024 4096 files [root@...]# grep -E "Limit|Max open files" /proc/17840/limits Limit Soft Limit Hard Limit Units Max open files 1024 4096 files [root@...]# grep -E "Limit|Max open files" /proc/17841/limits Limit Soft Limit Hard Limit Units Max open files 1024 4096 files *b) Squid configuration with max_filedesc 2048 and default nofile limit (1024/4096):* [root@...]# ps aux | grep squid root 7194 0.0 0.1 73524 3492 ? Ss May17 0:00 squid -f /etc/squid/squid.conf squid 7197 0.2 10.9 276080 210156 ? S May17 4:53 (squid) -f /etc/squid/squid.conf squid 7198 0.0 0.0 20080 1084 ? S May17 0:00 (unlinkd) [root@...]# grep -E "Limit|Max open files" /proc/7194/limits Limit Soft Limit Hard Limit Units Max open files 1024 4096 files [root@...]# grep -E "Limit|Max open files" /proc/7197/limits Limit Soft Limit Hard Limit Units Max open files *2048* 4096 files [root@...]# grep -E "Limit|Max open files" /proc/7198/limits Limit Soft Limit Hard Limit Units Max open files *2048* 4096 files - soft nofile limit was increased for processes running under squid user *c) Squid configuration with max_filedesc 8192 and default nofile limit (1024/4096):* [root@...]# ps aux | grep squid root 18734 0.0 0.1 73524 3492 ? Ss 14:00 0:00 squid -f /etc/squid/squid.conf squid 18737 0.3 0.6 80244 11860 ? S 14:00 0:00 (squid) -f /etc/squid/squid.conf squid 18740 0.0 0.0 20080 1088 ? S 14:00 0:00 (unlinkd) [root@...]# grep -E "Limit|Max open files" /proc/18734/limits Limit Soft Limit Hard Limit Units Max open files 1024 4096 files [root@...]# grep -E "Limit|Max open files" /proc/18737/limits Limit Soft Limit Hard Limit Units Max open files *8192* *8192* files [root@...]# grep -E "Limit|Max open files" /proc/18740/limits Limit Soft Limit Hard Limit Units Max open files *8192* *8192* files - both soft and hard nofile limits were increased for processes running under squid user I think, that the limits could be increased in tests b) and c) because the master process runs under the root user. Am I right or not? Or need I to increase the limits for the master proccess too? Thank you and with best regards, -- Karel Ziegler
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