# Re: backend fork/reader-process <-> sane_read

From: Matto Marjanovic (maddog@mir.com)
Date: Mon Feb 21 2000 - 07:06:06 PST

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  I just wanted to throw in my two cents on this, because I haven't heard
  something that I expected to hear in the whole thread on this issue....

  It's been my understanding that, originally, all the forking around in
  the backends was in order to implement asynchronous I/O, and the intent
  of asynchronous I/O (and sane_set_io_mode()) was not to tune the scanner
  speed, but to improve GUI response. Under async I/O, the GUI/frontend
  would not block while waiting for the backend to deliver a full buffer
  of data.

  Obviously, all the extra copying that goes on with sending scanlines
  from one process to another via pipes is not an efficiency gain, and
  that is kind of why I haven't bothered jumping through the hoops to
  add async I/O to the microtek backend. (But, my scanner also seems
  to have bigger buffers than some other scanners out there -- Hah-hah!
  At least they did *something* right.)

  -matt m.

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