首先出現這個提示的原因：應用程序打開的文件數量超過了系統設定值。
如何查看當前系統每個用戶最大允許打開文件數量：
[root@registry ~]# 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) 3820
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) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 3820
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
或者
[root@registry ~]# ulimit -n 1024
其中 open files (-n) 1024 表示每個用戶最大允許打開的文件數量是1024
#查看一下當前已有的連接數，以此來判斷open files 為1024 是否足夠
[root@registry ~]# lsof -n |awk '{print$2}'|sort |uniq -c |sort -nr |more
590 5458
445 1065
306 638
267 770
190 5682
189 5457
158 704
130 1194
117 681
81 1263
68 5419
66 640
62 1
60 5677
57 678
55 1067
51 9036
51 1196
48 5698
44 677
44 470
38 494
32 637
29 4430
20 4614
17 9250
14 4566
12 9256
12 9251
11 9254
11 9252
10 9255
10 693
9 9253
3 92
3 9037
3 9033
3 9
3 8964
3 8
3 726
其中第一列是打開的文件句柄數量，第二列是進程id號
通過句柄數量最多的進程，查看是哪個應用程序打開了最多的文件句柄，通過命令：
[root@registry ~]# ps -aef |grep PID
設置open files 數值的方法
1.臨時設置方法
[root@registry ~]# ulimit -n 4096 [root@registry ~]# 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) 3820 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 4096 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 3820 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited
這樣就可以把當前用戶的最大允許打開文件數量設置為4096，但這種設置方法在重啟后會還原為默認值。
2.永久設置方法
[root@registry ~]# vim /etc/security/limits.conf # End of file root soft nofile 65535 root hard nofile 65535 * soft nofile 65535 * hard nofile 65535
在文件末尾添加上述四行，其中后面兩行的 * 表示所有的用戶，也可以根據需要設置某一個用戶，比如www
# End of file root soft nofile 65535 root hard nofile 65535 www soft nofile 65535 www hard nofile 65535
注銷賬戶，重新登錄即可生效。
如果想查看某個進程最大允許打開的文件數量，可通過如下命令查看：
[root@registry ~]# top top - 15:39:21 up 101 days, 6:26, 1 user, load average: 0.33, 0.57, 0.52 Tasks: 70 total, 1 running, 69 sleeping, 0 stopped, 0 zombie %Cpu(s): 6.7 us, 0.0 sy, 0.0 ni, 93.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 3881824 total, 111956 free, 3505012 used, 264856 buff/cache KiB Swap: 2047996 total, 1001156 free, 1046840 used. 123968 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 12872 www 20 0 2738092 743948 2292 S 6.7 19.2 652:05.43 java 1 root 20 0 43380 2244 1352 S 0.0 0.1 4:11.26 systemd 2 root 20 0 0 0 0 S 0.0 0.0 0:00.31 kthreadd 3 root 20 0 0 0 0 S 0.0 0.0 28:18.97 ksoftirqd/0 5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H 7 root rt 0 0 0 0 S 0.0 0.0 0:00.00 migration/0 8 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcu_bh 9 root 20 0 0 0 0 S 0.0 0.0 33:52.08 rcu_sched 10 root rt 0 0 0 0 S 0.0 0.0 0:39.61 watchdog/0 12 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kdevtmpfs 13 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 netns 14 root 20 0 0 0 0 S 0.0 0.0 0:07.72 khungtaskd 15 root 0 -20 0 0 0 S 0.0 0.0 0:00.18 writeback 16 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kintegrityd 17 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 bioset 18 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kblockd 19 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 md 25 root 20 0 0 0 0 S 0.0 0.0 12:21.57 kswapd0 26 root 25 5 0 0 0 S 0.0 0.0 0:00.00 ksmd 27 root 39 19 0 0 0 S 0.0 0.0 0:17.32 khugepaged 28 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 crypto 36 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kthrotld 38 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kmpath_rdacd 39 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kpsmoused 40 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 ipv6_addrconf 59 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 deferwq 101 root 20 0 0 0 0 S 0.0 0.0 0:03.48 kauditd 225 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 ata_sff 233 root 20 0 0 0 0 S 0.0 0.0 0:00.00 scsi_eh_0 234 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 scsi_tmf_0 235 root 20 0 0 0 0 S 0.0 0.0 0:00.00 scsi_eh_1 236 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 scsi_tmf_1 240 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 ttm_swap 252 root 0 -20 0 0 0 S 0.0 0.0 1:07.64 kworker/0:1H 257 root 20 0 0 0 0 S 0.0 0.0 3:12.26 jbd2/vda1-8 258 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 ext4-rsv-conver 325 root 20 0 119080 5460 5316 S 0.0 0.1 5:27.58 systemd-journal 354 root 20 0 44032 8 4 S 0.0 0.0 0:00.08 systemd-udevd [root@registry ~]# cat /proc/12872/limits Limit Soft Limit Hard Limit Units Max cpu time unlimited unlimited seconds Max file size unlimited unlimited bytes Max data size unlimited unlimited bytes Max stack size 8388608 unlimited bytes Max core file size 0 unlimited bytes Max resident set unlimited unlimited bytes Max processes 65535 65535 processes Max open files 65535 65535 files Max locked memory 65536 65536 bytes Max address space unlimited unlimited bytes Max file locks unlimited unlimited locks Max pending signals 15089 15089 signals Max msgqueue size 819200 819200 bytes Max nice priority 0 0 Max realtime priority 0 0 Max realtime timeout unlimited unlimited us