[Bug 1896614] [NEW] Race condition when starting dbus services

[Victor Tapia]

Public bug reported:

In certain scenarios, such as high load environments or when "systemctl
daemon-reload" runs at the same time a dbus service is starting (e.g.
systemd-logind), systemd is not able to track properly when the service
has started, keeping the job 'running' forever.

The issue appears when systemd runs the "AddMatch" dbus method call to
track the service's "NameOwnerChange" once it has already ran. A working
instance would look like this:

https://pastebin.ubuntu.com/p/868J6WBRQx/

A failing instance would be:

https://pastebin.ubuntu.com/p/HhJZ4p8dT5/

I've been able to reproduce the issue on Bionic (237-3ubuntu10.42)
running:

sudo systemctl daemon-reload & sudo systemctl restart systemd-logind

** Affects: systemd (Ubuntu)
     Importance: Undecided
         Status: New

** Affects: systemd (Ubuntu Bionic)
     Importance: Undecided
         Status: New


** Tags: sts

** Tags added: sts

** Also affects: systemd (Ubuntu Bionic)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1896614

Title:
  Race condition when starting dbus services

Status in systemd package in Ubuntu:
  New
Status in systemd source package in Bionic:
  New

Bug description:
  In certain scenarios, such as high load environments or when
  "systemctl daemon-reload" runs at the same time a dbus service is
  starting (e.g. systemd-logind), systemd is not able to track properly
  when the service has started, keeping the job 'running' forever.

  The issue appears when systemd runs the "AddMatch" dbus method call to
  track the service's "NameOwnerChange" once it has already ran. A
  working instance would look like this:

  https://pastebin.ubuntu.com/p/868J6WBRQx/

  A failing instance would be:

  https://pastebin.ubuntu.com/p/HhJZ4p8dT5/

  I've been able to reproduce the issue on Bionic (237-3ubuntu10.42)
  running:

  sudo systemctl daemon-reload & sudo systemctl restart systemd-logind

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