Neo4j WARNING: Max 1024 open files allowed, minimum of 40 000 recommended. See the Neo4j manual

Question

I installed Neo4j on Ubuntu 12.04 using these instructions: http://www.neo4j.org/download/linux

wget -O - http://debian.neo4j.org/neotechnology.gpg.key | apt         


        

Answer 1

You need to add the following entries into the /etc/security/limits.conf file

root   soft    nofile  40000
root   hard    nofile  40000

You need to start the service as root or using sudo

When you do that, the user that ends up starting the service is the root user.

If you dont have an entry in the file for the root user, then it would not work.

So, you just need to add those entries in the file and then reboot your server.

I had the same problem and that is how I was able to resolve it.

Answer 2

This worked for me on Arch Linux (x86_64), where prior to these modifications ulimit -n was 1024):

1. Edit /etc/pam.d/su, add:

   session required pam_limits.so

2. Edit both

   /etc/systemd/system.conf

   /etc/systemd/user.conf

   add to each (whatever value you desire: I chose 100,000):

   DefaultLimitNOFILE=100000

3. Reboot.

   $ ulimit -n 100000

Based on

• https://ro-che.info/articles/2017-03-26-increase-open-files-limit

• https://wiki.archlinux.org/index.php/Limits.conf

Answer 3

You can set the hard limits in /etc/security/limits.conf and restart the server to make it into effect.

But with current session, you can run

ulimit -n 40000

Answer 4

The solutions posted by @israel and by @Tomasz Swider did not work for me (I am running Ubuntu 14.04). However, I could get rid of this warning by modifying the file /etc/init.d/neo4j-service as suggested by @zwol in the comments below the question:

I added the line ulimit -n 40000 to the do_start() method in this file. In my case this method then looks as follows:

do_start()
{
        # Return
        #   0 if daemon has been started
        #   1 if daemon was already running
        #   2 if daemon could not be started
        ulimit -n 40000
        start-stop-daemon --chuid ${NEO_USER} --start --quiet --pidfile $PIDFILE --exec $DAEMON --test > /dev/null \
                || return 1
        start-stop-daemon --chuid ${NEO_USER} --start --quiet --pidfile $PIDFILE --exec $DAEMON -- \
                $DAEMON_ARGS \
                || return 2
}

When I then start the service by using the command

sudo service neo4j-service start

it starts without the warning and returns the following message:

Starting Neo4j Server...WARNING: not changing user
process [9921]... waiting for server to be ready...... OK.
http://localhost:7474/ is ready.

I am not sure whether that is the way to go but as written above, that was the only solution that has worked for me so far to get rid of this warning.

EDIT:

Have not tested it, but seems there is now an easier solution available: see @Schrodinger's'Cat's answer.

Answer 5

I applied the changes as suggested in previous answers

root   soft    nofile  40000
root   hard    nofile  40000

neo4j   soft    nofile  40000 
neo4j   hard    nofile  40000

to

/etc/security/limits.conf

Nevertheless I still got the warning about only 1024 open files being allowed. The command

ulimit -a

did show only 1024 open files allowed.

The trick was to log out of the server, then log back in. In the new session the values of the new limits-configuration were applied and I could

service neo4j-server restart

with 40.000 open files allowed.

Answer 6

Just check once the current value from below command ulimit -n and ulimit -a

And you can edit the value on path below /etc/security/limit.conf