ZA 的BOSS 最近出现Too many open files 异常，这个异常一般是由于打开文件数过多引起， 最常见原因是某些连接一致未关闭
记录一些排查用到的指令
查看每个用户最大允许打开文件数量
ulimit -a
[root@haiwai ~]# ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 22610
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 10240
cpu time (seconds, -t) unlimited
max user processes (-u) 22610
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
临时处理方法： 调整打开文件数大小
[root@haiwai ~]# ulimit -n 2048
[root@haiwai ~]#
[root@haiwai ~]# ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 22610
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 2048
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 10240
cpu time (seconds, -t) unlimited
max user processes (-u) 22610
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
[root@haiwai ~]#
其中 open files (-n) 1024 表示每个用户最大允许打开的文件数量是1024
查看某一个进程打开文件数
[root@haiwai ~]# lsof -p [PID] |wc -l
例如：
[root@haiwai ~]# lsof -p 25102 |wc -l
200
[root@haiwai ~]#
查看8080端口连接 和9090 端口连接
[root@haiwai ~]# netstat -nat|grep -i "8080"|wc -l
1
netstat -an会打印系统当前网络链接状态，而grep -i "8080"是用来提取与8080端口有关的连接的，wc -l进行连接数统计。
查看连接IP等详情
[root@haiwai ~]# netstat -an |grep 8080
tcp 0 0 :::8080 :::* LISTEN
tcp 0 1 ::ffff:192.168.20.60:13086 ::ffff:10.150.6.62:8080 SYN_SENT
tcp 0 0 ::ffff:192.168.20.60:8080 ::ffff:192.168.20.174:52900 ESTABLISHED
tcp 0 1 ::ffff:192.168.20.60:13087 ::ffff:10.150.6.62:8080 SYN_SENT
查看所有已经建立的连接
netstat -an会打印系统当前网络链接状态，而grep ESTABLISHED 提取出已建立连接的信息。 然后wc -l统计。
[root@haiwai ~]# netstat -na|grep ESTABLISHED
tcp 0 0 192.168.20.60:22 192.168.7.189:3974 ESTABLISHED
tcp 0 48 192.168.20.60:22 192.168.20.174:58644 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:39923 ::ffff:192.168.20.155:1521 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:21637 ::ffff:192.168.20.155:1521 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:49400 ::ffff:192.168.20.155:1521 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:44992 ::ffff:192.168.20.155:1521 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:1521 ::ffff:192.168.7.41:51609 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:28370 ::ffff:192.168.20.155:1521 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:1521 ::ffff:192.168.7.41:51608 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:1521 ::ffff:192.168.7.41:49907 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:48748 ::ffff:192.168.20.155:1521 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:1521 ::ffff:192.168.20.174:49989 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:27656 ::ffff:192.168.20.155:1521 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:31186 ::ffff:192.168.20.155:1521 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:30680 ::ffff:192.168.20.155:1521 ESTABLISHED
tcp 0 0 ::ffff:192.168.20.60:22216 ::ffff:192.168.20.155:1521 ESTABLISHED