MongDB 启动警告 WARNING: soft rlimits too low

# mongo
MongoDB shell version: 3.0.2
connecting to: test
Server has startup warnings: 
2015-05-09T12:34:19.688-0700 I CONTROL  [initandlisten] 
2015-05-09T12:34:19.688-0700 I CONTROL  [initandlisten] ** WARNING: soft rlimits too low. rlimits set to 1024 processes, 64000 files. Number of processes should be at least 32000 : 0.5 times number of files.
> 

mongodb当前限制：1024 processes, 64000 files

mongodb建议要求：processes = 0.5*files=32000（至少）

所以需要将 processes  从1024 改为 32000 或更大.

查看当前mongodb进程信息：

[root@localhost ~]# ps -ef | grep mongod

mongod   24283     1  0 12:35 ?        00:00:04 /usr/bin/mongod -f /etc/mongod.conf
root     24240 22049  0 12:45 pts/2    00:00:00 grep mongod

[root@localhost ~]# cat /proc/24283/limits

#可以看到限制：Max processes，Max open files 

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            10485760             unlimited            bytes     
Max core file size        0                    unlimited            bytes     
Max resident set          unlimited            unlimited            bytes     
Max processes             1024                 32000                processes 
Max open files            64000                64000                files     
Max locked memory         65536                65536                bytes     
Max address space         unlimited            unlimited            bytes     
Max file locks            unlimited            unlimited            locks     
Max pending signals       14833                14833                signals   
Max msgqueue size         819200               819200               bytes     
Max nice priority         0                    0                    
Max realtime priority     0                    0                    
Max realtime timeout      unlimited            unlimited            us    

修改 Max processes 或者 files ，有几种方法：

方法一：

修改配置文件 /etc/security/limits.d/90-nproc.conf  

[root@localhost ~]# vi /etc/security/limits.d/90-nproc.conf 

*          soft    nproc     1024
改为:
*          soft    nproc     32000

重启 mongod 服务：

[root@localhost ~]# service mongod restart

方法二：

修改配置文件 /etc/security/limits.conf，添加配置信息：

[root@localhost ~]# vi /etc/security/limits.conf

mongod soft nofile 64000
mongod hard nofile 64000
mongod soft nproc 32000
mongod hard nproc 32000

重启 mongod 服务：

[root@localhost ~]# service mongod restart

也可以查看 limits.conf 更多配置信息和使用方法：

[root@localhost ~]# man limits.conf

查看系统限制：

[root@localhost ~]# 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) 14833
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) 14833
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

mongodb推荐设置：

-f (file size): unlimited
-t (cpu time): unlimited
-v (virtual memory): unlimited
-n (open files): 64000
-m (memory size): unlimited
-u (processes/threads): 64000

直接在当前shell中设置：ulimit -n <value>

ulimit -f unlimited
ulimit -t unlimited
ulimit -v unlimited
ulimit -n 64000
ulimit -m unlimited
ulimit -u 64000

若要系统启动时在所有生效，将上面的 ulimit 添加到 /etc/profile 

[root@localhost ~]# vi /etc/profile

参考： UNIX ulimit Settings