[sane-devel] 3 mins delay at xscanimage startup due to querying hpiod

[Volker Barth]

Dear all,

I recently bought my first scanner (Canon Lide 25), which is reported
to work with the plustek backend. I'm running Kubuntu Dapper and have
the most recent ubuntu binary packages 'libsane' and 'sane' installed.

My problem is that when I start xscanimage it takes 3:10 minutes until
the GUI shows up, which is quite a while. After setting
SANE_DEBUG_XSCANIMAGE to 4 I found that it stays all the time in the
[init] section. Meanwhile, the syslog gives the following messages:

  scanimage: unable to open /var/run/hplip/hpiod.port: No such file or directory: prnt/hpijs/hplip_api.c 84

when xscanimage is being started and when [init] has finished and the
GUI shows up:  

  xscanimage: unable to connect hpiod socket 50000: Connection timed out: prnt/hpijs/hplip_api.c 703
  xscanimage: ProbeDevices(): unable to send message: Bad file descriptor

Because of the first message I tried to start the hpiod daemon and
hplip, although I did not understand why a Canon scanner on the
plustek backend might require this daemon... The syslog told me:

  hpiod: 0.9.7 accepting connections at 45490... 

When starting xscanimage anew, the only improvement was that the first
message complaining about the missing hpiod.port disappeared, but the
rest remained very similar (after 190 seconds of waiting):

  xscanimage: unable to connect hpiod socket 45490: Connection timed out: prnt/hpijs/hplip_api.c 703 
  xscanimage: ProbeDevices(): unable to send message: Bad file descriptor

This behaviour does not change even when I start xscanimage as
root. In any case, after the GUI shows up, the scanner works
apparently without problems, so it's only the looong delay that
puzzles me.

My questions:
- Why does xscanimage (or the KDE frontend kooka, or xsane, which I
  all tried as well) try to connect to hpiod when there is apparently no
  device present that depends on this daemon?

- Is there a way to stop xscanimage to query the hpiod socket, or at
  least to shorten the time it tries to connect to it?

- Do you think that compiling sane from source offers a chance to
  circumvent this problem (e.g. because there is an option to build
  sane without querying hpiod)?

Thanks for your help and suggestions.

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