[Bug 1896614] Re: Race condition when starting dbus services

[Dimitri John Ledkov]

restarting systemd-logind is not safe, as existing sessions can be
logged out.

also performing daemon-reload, mid-boot, also is not safe.

Can you explain the usecase and why these actions are performed
together, racing each other?

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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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