.. /*  
    * This file is part of the SavaPage project <https://www.savapage.org>.
    * Copyright (c) 2026 Datraverse B.V.
    * Author: Rijk Ravestein.
    *
    * SPDX-FileCopyrightText: (c) 2020 Datraverse B.V. <info@datraverse.com>
    * SPDX-License-Identifier: CC-BY-SA-4.0
    *
    * For more information, please contact Datraverse B.V. at this
    * address: info@datraverse.com
    */

.. _ch-tuning-ulimit:

Linux User Limits
-----------------

.. contents:: |RST_TABLE_OF_CONTENTS|
   :depth: 2
   :local:

.. _ch-tuning-ulimit-intro:

Introduction
~~~~~~~~~~~~

SavaPage server may run out of file descriptors as the system
defaults are normally very low. A file descriptor (FD) is a handle
created by a process when a file is opened. Each process can use a
limited number of FDs as specified per user in an OS level user limit.

Beware that apart from “regular” files that are accessed by |PRODUCT_NAME|
from disk, each incoming request that uses a TCP socket also consumes
one file descriptor from the total available for the process.

.. _ch-tuning-ulimit-sysvinit:

SysVinit User Limits
~~~~~~~~~~~~~~~~~~~~

On Debian based systems the number of process FDs for the ``savapage`` user
can be increased as follows.

Edit the file Edit ``/etc/security/limits.conf`` like this:

.. code-block:: bash

   sudo vi /etc/security/limits.conf

... and add the following lines at the end of the file:

.. code-block:: text

   savapage    hard    nofile    65536
   savapage    soft    nofile    65536

Next, open ``/etc/pam.d/su`` like this:

.. code-block:: bash

   sudo vi /etc/pam.d/su

... and uncomment the following line:

.. code-block:: text

   session    required   pam_limits.so

You also need to edit the ``/etc/pam.d/common-session`` and
``/etc/pam.d/common-session-noninteractive`` files. Open the files like
this:

.. code-block:: bash

   sudo vi /etc/pam.d/common-session
   sudo vi /etc/pam.d/common-session-noninteractive

and for each file add the following line to the end:

.. code-block:: text

   session required pam_limits.so

Finally, check whether the settings are applied with this command:

.. code-block:: bash

   sudo su - savapage -c "ulimit -n"


This should output the value ``65536``.

.. _ch-tuning-ulimit-systemd:

Systemd User Limits
~~~~~~~~~~~~~~~~~~~

Systemd ignores ``ulimit`` values as described in the previous section,
and has its own equivalent that can be used per service. The best way to
set user limits for the ``savapage.service`` is by an *override*, that
will have the last say over any SavaPage default.

Check the ``/lib/systemd/system/savapage.service`` unit to see
if the value of the ``LimitNOFILE`` directive is to your liking. This
directive corresponds to ``ulimit -n`` (open files) and defaults to ``65536``.

.. code-block:: bash

   cat /lib/systemd/system/savapage.service | grep LimitNOFILE``

If this directive is absent, or if you want to override the value, edit
the service unit with this command:

.. code-block:: bash

   sudo systemctl edit savapage

This launches a text editor for creating 
this file: ``/etc/systemd/system/savapage.service.d/override.conf``

Add the following lines, using your own choice (e.g. 98304):

.. code-block:: ini

   [Service]
   LimitNOFILE=98304


Save the file and close the editor. Usually, after you edited a systemd
unit file, for it to take effect, you need to run:

.. code-block:: bash

   sudo systemctl daemon-reload


However, the ``systemctl edit`` command automatically did this for you.
You can check the effect of the override with this command:

.. code-block:: bash

    systemctl cat savapage.service | grep LimitNOFILE

... the last line should show:

.. code-block:: bash

   LimitNOFILE=98304

Restart SavaPage for the changes to take effect, and check if the
override has effect with this command:

.. code-block:: bash

   systemctl status savapage.service

Notice the Drop-In ``override.conf`` as shown below:

.. code-block:: bash

   savapage.service - SavaPage Open Print Portal
     Loaded: loaded (/lib/systemd/system/savapage.service; enabled; vendor preset: enabled)
     Drop-In: /etc/systemd/system/savapage.service.d
              |- override.conf
     Active: active (running) since ...


.. important::

   Check if the “open files” override value is shown correctly in the
   :ref:`Host System <ch-webapp-admin-about-host-system>` section of the
   Admin Web App, since this is the actual value that the |PRODUCT_NAME|
   server process uses.