linux open file number too many open files solution

too many open files

The reason for this prompt is that the number of file/socket connections opened by the program exceeds the system settings.

View the maximum number of open files per user

ulimit -a

1. fdipzone@ubuntu:~$ ulimit -a  
2. core file size          (blocks, -c) 0  
3. data seg size           (kbytes, -d) unlimited  
4. scheduling priority             (-e) 20  
5. file size               (blocks, -f) unlimited  
6. pending signals                 (-i) 16382  
7. max locked memory       (kbytes, -l) 64  
8. max memory size         (kbytes, -m) unlimited  
9. open files                      (-n) 1024  
10. pipe size            (512 bytes, -p) 8  
11. POSIX message queues     (bytes, -q) 819200  
12. real-time priority              (-r) 0  
13. stack size              (kbytes, -s) 8192  
14. cpu time               (seconds, -t) unlimited  
15. max user processes              (-u) unlimited  
16. virtual memory          (kbytes, -v) unlimited  
17. file locks                      (-x) unlimited  

Where open files (-n) 1024 indicates that the maximum number of files allowed to open per user is 1024

View the number of files open on the current system

1. lsof | wc -l  
2. watch "lsof | wc -l"  

View the number of open files for a process

1. lsof -p pid | wc -l  
2. lsof -p 1234 | wc -l  

Setting the open files numerical method

ulimit -n 2048

1. fdipzone@ubuntu:~$ ulimit -n 2048  
2. fdipzone@ubuntu:~$ ulimit -a  
3. core file size          (blocks, -c) 0  
4. data seg size           (kbytes, -d) unlimited  
5. scheduling priority             (-e) 20  
6. file size               (blocks, -f) unlimited  
7. pending signals                 (-i) 16382  
8. max locked memory       (kbytes, -l) 64  
9. max memory size         (kbytes, -m) unlimited  
10. open files                      (-n) 2048  
11. pipe size            (512 bytes, -p) 8  
12. POSIX message queues     (bytes, -q) 819200  
13. real-time priority              (-r) 0  
14. stack size              (kbytes, -s) 8192  
15. cpu time               (seconds, -t) unlimited  
16. max user processes              (-u) unlimited  
17. virtual memory          (kbytes, -v) unlimited  
18. file locks                      (-x) unlimited  

In this way, the maximum number of open files allowed by the current user can be set to 2048, but this setting method will be restored to the default value after reboot.

Permanent Setup Method

The first * represents all users and can set up a user as needed, for example

1. fdipzone soft nofile 8192  
2. fdipzone hard nofile 8192  

It will take effect after the change is cancelled.