[argyllcms] Re: Spotread stalling sometimes under Windows

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 13 Nov 2015 14:25:53 +1100

François Simond wrote:

It is like spotread.exe never received one of the command.

Sounds like a race condition - the thread doing the stdin read
probably got killed just as the character arrived. I don't have any
clever ideas for solving this at the moment, since stdin has
to be poll-able and also readable in other ways in other places in
the code.

However when maxing out the CPU with multiple threads or an external
program, it is producing the error usually before completing 35
readings.

Don't max out the CPU(s). You may well find that other things fail too -
for some instruments (i.e the i1pro, i1d3 doing refresh rate measurement etc.
etc.),
there are some real time aspects to making it go. If the thread response time
is too
unreasonable, you may get timeouts where the instrument gives up waiting for
the USB read. (i.e. accessing a color instrument is not a batch process!).

Meanwhile I ran the same stress test on another Linux machine with the
i1Pro, and instead of failing quickly it reached the point where it
requests a new calibration after almost a thousand readings:

Result is XYZ: 265.783643 270.932687 335.207395, D50 Lab: 145.713071
4.023201 -40.338008

Got reading: 962 elapsed: 1374ms
Spot read needs a calibration before continuing

Yep - the calibration has timed out. Time to re-cal.
(although it should probably have been done much earlier!).

Argyll 1.4.0 was not affected by the issue described and it seems
there was a rewrite after that, when comparing the version's code.
Maybe the older routines used to poll Windows stdin were more reliable?

Looks pretty much the same, except it didn't wait as long for the thread
to start, which would seem to be more likely to make it less reliable, since
there would be a smaller window to read a line, and a larger proportion of
the time the thread will be being killed.

Under Windows, spotread fails after 4 readings (log 5)
On Linux, it went on up to 875 readings before asking for the sensor
re-calibration.

Spotread certainly doesn't fail with the i1pro Rev A after 4 readings
(or any small number) running on my MSWin machine. I would have
notices a long time ago, since I often test things using spotread.
Does it only do this when running via your java program ?
Was your machine busy or idle ?

Graeme Gill.


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