Bug#984692: cups-daemon: "dbus" notifier stays hanging after showing the notification

[Igor Liferenko <igor.liferenko@gmail.com>]

Package: cups-daemon
Version: 2.3.3op2-3
Severity: normal
X-Debbugs-Cc: igor.liferenko@gmail.com

Dear Maintainer,

After printing a file I get notification that document is sent to printer
and then that printing is finished.

The problem is that dbus notifier process stays alive after having done
its job. Most probably the reason is that the process which calls
the notifier does not close the pipe and the dbus notifier process
keeps waiting for data to be read instead of getting EOF.

Following are the outputs of "systemctl status cups" before and after
printing a document. Notice the process list in the end of each.

● cups.service - CUPS Scheduler
     Loaded: loaded (/lib/systemd/system/cups.service; enabled; vendor preset: enabled)
     Active: active (running) since Sun 2021-03-07 15:44:27 +07; 12s ago
TriggeredBy: ● cups.path
             ● cups.socket
       Docs: man:cupsd(8)
   Main PID: 5019 (cupsd)
     Status: "Scheduler is running..."
      Tasks: 1 (limit: 2142)
     Memory: 3.4M
        CPU: 18ms
     CGroup: /system.slice/cups.service
             └─5019 /usr/sbin/cupsd -l

---------------

● cups.service - CUPS Scheduler
     Loaded: loaded (/lib/systemd/system/cups.service; enabled; vendor preset: enabled)
     Active: active (running) since Sun 2021-03-07 15:44:27 +07; 19s ago
TriggeredBy: ● cups.path
             ● cups.socket
       Docs: man:cupsd(8)
   Main PID: 5019 (cupsd)
     Status: "Scheduler is running..."
      Tasks: 2 (limit: 2142)
     Memory: 4.8M
        CPU: 123ms
     CGroup: /system.slice/cups.service
             ├─5019 /usr/sbin/cupsd -l
             └─5025 /usr/lib/cups/notifier/dbus dbus://

Thanks,
Igor

P.S.
This may be relevant:
https://bugzilla.redhat.com/show_bug.cgi?id=1026949

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-3-amd64 (SMP w/1 CPU thread)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages cups-daemon depends on:
ii  adduser              3.118
ii  bc                   1.07.1-2+b2
ii  init-system-helpers  1.60
ii  libavahi-client3     0.8-5
ii  libavahi-common3     0.8-5
ii  libc6                2.31-9
ii  libcups2             2.3.3op2-3
ii  libdbus-1-3          1.12.20-1
ii  libgssapi-krb5-2     1.18.3-4
ii  libpam0g             1.4.0-4
ii  libpaper1            1.1.28+b1
ii  libsystemd0          247.3-1
ii  lsb-base             11.1.0
ii  procps               2:3.3.16-5
ii  ssl-cert             1.1.0

Versions of packages cups-daemon recommends:
ii  avahi-daemon  0.8-5
ii  colord        1.4.5-3
ii  cups-browsed  1.28.7-1
ii  ipp-usb       0.9.17-1

Versions of packages cups-daemon suggests:
ii  cups                                       2.3.3op2-3
pn  cups-bsd                                   <none>
ii  cups-client                                2.3.3op2-3
ii  cups-common                                2.3.3op2-3
ii  cups-filters                               1.28.7-1
pn  cups-pdf                                   <none>
ii  cups-ppdc                                  2.3.3op2-3
ii  cups-server-common                         2.3.3op2-3
pn  foomatic-db-compressed-ppds | foomatic-db  <none>
ii  ghostscript                                9.53.3~dfsg-7
ii  poppler-utils                              20.09.0-3.1
ii  smbclient                                  2:4.13.4+dfsg-1
ii  udev                                       247.3-1

-- Configuration Files:
/etc/cups/cups-files.conf changed [not included]

-- no debconf information