Max user process nproc limit recommendations

By default the "max user process" (nproc) value on RHEL servers is set to 1024, which is too low for a Columbus installation. If the process limit is reached for any of the Linux user accounts used by the Columbus server then resource errors are possible. The 'columbus' and 'acapella' Linux users are most likely to be affected by this. If the resource limit is reached then the following error conditions are likely...

Limit reached for columbus user:

The postgres database processes cannot create any new threads and so crashes. If we check the status of the Columbus service we see the following error associated with the database component - "su: cannot set user id. Resource temporarily unavailable ". The server must be restarted to correct.

Limit reached for acapella user:

We see acc slave server crashes which render the user session temporarily unavailable, Error 500 messages in the interface are common.


We suggest to raise the nproc limit on a system-wide level so that all OS user accounts are accounted for.


i) To set the nproc Hard limit to 16384 for all users, add the following line to /etc/security/limits.conf

* hard nproc 16384

ii) To set the nproc Soft limit to 16384 for all users, add the following line /etc/security/limits.d/90-nproc.conf

* soft nproc 16384