How to Fix D-Bus Service Failures

[Abdullah Yıldız]

Hi,

I have been experiencing an issue for a couple of days in our system,
and I suspect that D-Bus service somehow could not handle the requests
when there are many users active in the system.

When I check the system logs with journalctl -xe, I noticed that there
are some errors flagged:

Mar 05 07:46:08 compute-server xdg-desktop-por[35472]: error:
GDBus.Error:org.freedesktop.DBus.Error.LimitsExceeded: The maximum
number of active connections has been reached
Mar 05 07:46:18 compute-server dbus[1350]: [system] Failed to activate
service 'org.freedesktop.hostname1': timed out
Mar 05 07:46:24 compute-server dbus[1350]: [system] Connection has not
authenticated soon enough, closing it (auth_timeout=30000ms, elapsed:
30006ms)

...
:Mar 05 12:19:23 compute-server gnome-session[15079]:
gnome-session-binary[15079]: WARNING: Unable to inhibit system:
GDBus.Error:org.freedesktop.DBus.Error.AccessDenied: Permission denied
:Mar 05 12:20:47 compute-server gnome-session-binary[5917]: WARNING:
Unable to inhibit system:
GDBus.Error:org.freedesktop.DBus.Error.AccessDenied: Permission denied

...
Mar 06 11:16:53 compute-server dbus[1350]: [system] Connection has not
authenticated soon enough, closing it (auth_timeout=30000ms, elapsed:
30006ms)
Mar 06 11:16:53 compute-server sshd[7677]: pam_systemd(sshd:session):
Failed to create session: Connection reset by peer

This is what I observe when I check /usr/share/dbus-1/session.conf:

  <!-- the memory limits are 1G instead of say 4G because they can't
exceed 32-bit signed int max -->
  <limit name="max_incoming_bytes">1000000000</limit>
  <limit name="max_incoming_unix_fds">250000000</limit>
  <limit name="max_outgoing_bytes">1000000000</limit>
  <limit name="max_outgoing_unix_fds">250000000</limit>
  <limit name="max_message_size">1000000000</limit>
  <!-- We do not override max_message_unix_fds here since the
in-kernel
       limit is also relatively low -->
  <limit name="service_start_timeout">120000</limit>
  <limit name="auth_timeout">240000</limit>
  <limit name="pending_fd_timeout">150000</limit>
  <limit name="max_completed_connections">900</limit>
  <limit name="max_incomplete_connections">92</limit>
  <limit name="max_connections_per_user">100000</limit>
  <limit name="max_pending_service_starts">10000</limit>
  <limit name="max_names_per_connection">50000</limit>
  <limit name="max_match_rules_per_connection">50000</limit>
  <limit name="max_replies_per_connection">50000</limit>

I want to understand that overriding some of the D-Bus specific values
(as shown below) would help to fix the issue:

<busconfig>
 <!-- default for this is 900 -->
 <limit name="max_completed_connections">32768</limit>
 <!-- default for this is 92 -->
 <limit name="max_incomplete_connections">1000</limit>
 <!-- default for this is 100000 -->
 <limit name="max_connections_per_user">150000</limit>
</busconfig>

Thank you in advance.

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