mongodb : Increasing max connections in mongodb

Question

i need your help in solving this

this is the result of my ulimit -a on my linux server

   core file size          (blocks, -c) 0
schedu         


        

Answer 1

It seems MongoDB has no limit on incoming connections and you should modify system-wide limit, see official doc:

Unless constrained by system-wide limits, MongoDB has no limit on incoming connections. On Unix-based systems, you can modify system limits using the ulimit command, or by editing your system’s /etc/sysctl file. See UNIX ulimit Settings for more information.

Recommended ulimit Settings(offical doc):

-f (file size): unlimited

-t (cpu time): unlimited

-v (virtual memory): unlimited

-n (open files): 64000

-m (memory size): unlimited

-u (processes/threads): 64000

Remember to restart your mongod and mongos instances after changing the ulimit settings to ensure that the changes take effect.

Source: number-of-connections recommended-ulimit-settings

Answer 2

Have you tried:

--maxConns arg       max number of simultaneous connections

(Source: mongod documentation)

Answer 3

You also need bump up the number of file descriptors and number of file descriptors per process that the Linux kernel allows.

In Linux, this should be configured by editing the file at /proc/sys/fs/file-max or by the sysctl utility.

• Edit the /etc/sysctl.conf file and add fs.file-max = 50000. This sets the maximum file descriptors that can run as a system-wide limit.
• Running ulimit -n 50000 sets the user-wide limit for the maximum number of file descriptors open.

Check this link for a more descriptive write-up for editing the limits on a linux machine: http://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/

Answer 4

Method 1 If you use systemd (systemctl restart mongod)

sudo mkdir /etc/systemd/system/mongod.service.d/
sudo vi /etc/systemd/system/mongod.service.d/limits.conf

then add:

[Service]
LimitFSIZE=infinity
LimitCPU=infinity
LimitAS=infinity
LimitMEMLOCK=infinity
LimitNOFILE=64000
LimitNPROC=64000

Then execute:

systemctl daemon-reload
systemctl restart mongod

Method 2 If NO systemd (service mongod restart)

sudo vi /etc/security/limits.d/99-mongodb.conf

Add something like:

*       -       nproc   64000
*       -       nofile  64000
*       -       fsize   unlimited
*       -       cpu     unlimited
*       -       memlock unlimited
*       -       as      unlimited
*       -       rss     unlimited

Note that * it's a wildcard. But you could use a specific user or group. Then restart session and mongod.

Answer 5

You might need to change the hard limits in /etc/limits.conf or /etc/security/limits.conf depending on your distribution.