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Author Topic: Maximum spool file size when using Mac/CUPS?  (Read 7452 times)

JohnHeerema

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Maximum spool file size when using Mac/CUPS?
« on: August 30, 2012, 09:10:00 pm »

I've noticed that when I make large prints on my Epson 9900 using Mac Snow Leopard and Lightroom, I sometimes get a message from CUPS (the Common Unix Printing System used by MacOS) that it can't open the spool file. This messages have the form: "can't open `/private/var/spool/cups/tmp/000ef50451e47'." I believe that this is a CUPS issue, and not specifically related to Lightroom.

When I look at the CUPS log (which you can do by pointing a browser to localhost:631), it appears that this happens when the spool file size exceeds about 2Gb. If I reduce the print resolution, or switch from 16-bit output to 8-bit output, the print jobs complete normally.

This suggests to me that CUPS may still be using 32-bit code, and that it chokes when the spool file is bigger than about 2^31 bytes long. Mr. Google surprised me by not providing a ready answer to this question - does anyone know if this is a CUPS limitation? Any workarounds, other than reducing the print file size?

Thanks!
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Wayne Fox

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #1 on: August 31, 2012, 02:28:26 am »

Curious by what size you are trying to print.  I've printed 96x44" at 360dpi but I don't remember if I did it at 16 bit or 8 bit.  Visual difference between 8 bit and 16 bit is pretty my imperceptible ... I'd certainly try that first.  But no clue if it's an OS issue ...
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francois

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #2 on: August 31, 2012, 02:55:53 am »

Mac OS X supports file sizes above 2GB, for CUPS I don't know. It would be interesting to see if a more recent version of CUPS (means upgrading to OS X 10.7 or 10.8 or do it "manually") would allow printing your large files.
Try to find a friend with a 10.7 or 10.8 Mac…

By the way, any message in the Console during printing?

Edit: typo correction
« Last Edit: August 31, 2012, 11:01:26 am by francois »
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Francois

JohnHeerema

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #3 on: August 31, 2012, 10:53:10 am »

Quote
Curious by what size you are trying to print.  I've printed 96x44" at 360dpi but I don't remember if I did it at 16 bit or 8 bit.

Hi Wayne,

I'm trying to print 66x44" and 120x44" at 360 dpi. As you say, my eyes aren't good enough to readily tell the difference between 8 bit output and 16 bit output. Still though, I'd like to use 16 bit output if possible. There are quite a few of us on LULA making big prints, so I'm surprised that this hasn't come up as an issue before - it makes me think that there maybe be something in my configuration that's causing the limitation.

Thanks,
John
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JohnHeerema

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #4 on: August 31, 2012, 11:07:25 am »

Quote
It would be interesting to see if a more recent version of CUPS (means upgrading to OS X 10.7 or 10.8 or do it "manually") would allow printing your large files.

Hi Francois,

I had also wondered if more recent versions of the CUPS would allow for larger spool files, so I've taken a trip through the documentation (for me, Lion or Mountain Lion would be an OS downgrade, so I'd prefer not to go there until absolutely forced to).

The documentation for the CUPS raster format says that "Each file begins with a 32-bit synchronization word". This appears to include the latest version in www.cups.org, which is version 1.5, so there may not be a workaround.

Cheers,
John
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lfeagan

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #5 on: August 31, 2012, 11:55:25 am »

The documentation for the CUPS raster format says that "Each file begins with a 32-bit synchronization word". This appears to include the latest version in www.cups.org, which is version 1.5, so there may not be a workaround.

The 32-bit synchronization word has nothing to do with cups being 32-bit. It is used to identify machine and CUPS version-specific information about the encoding and format of the remainder of the file. On Lion and Mountain Lion, which I have at my ready disposal, I know that cups is a universal binary with both 32- and 64-bit variants.

From reading the rest of that spec page, I cannot see any reason why CUPS would not support a file as large as the OS + file system are capable of. And that page was rather fascinating to read, as a programmer.
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Lance

Nikon: D700, D800E, PC-E 24mm f/3.5D ED, PC-E 45mm f/2.8D ED, PC-E 85mm f/2.8D, 50mm f/1.4G, 14-24 f/2.8G ED, 24-70 f/2.8G ED, 70-200 f/2.8G ED VR II, 400mm f/2.8G ED VR
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JohnHeerema

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #6 on: August 31, 2012, 12:55:29 pm »

Hi Lance,

I looked at the documentation more carefully, and as you say, the synch word just contains a specific constant, so I think that you're correct in thinking that the raster file isn't intrinsically limited to 2 Gb.

The error log isn't any help (tail -f /private/var/log/cups/error_log), so the only clue I have is CUPS reporting that it can't open the raster file.

Every Mac owner I know has avoided Lion like the plague, so I can't easily try this on another version of the OS. Are there any Mac users who have been successful in printing bigger files?

Thanks,
John
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Wayne Fox

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #7 on: August 31, 2012, 04:08:29 pm »

Hi Wayne,

I'm trying to print 66x44" and 120x44" at 360 dpi. As you say, my eyes aren't good enough to readily tell the difference between 8 bit output and 16 bit output. Still though, I'd like to use 16 bit output if possible. There are quite a few of us on LULA making big prints, so I'm surprised that this hasn't come up as an issue before - it makes me think that there maybe be something in my configuration that's causing the limitation.

Thanks,
John

I'm not sure it's about your "eyes" ... i just don't think the printer gamuts really require 16bit data to achieve the quality. I'm not even sure it's "measureable", and to be honest, I'm not sure the OS/application/printer driver/printer support a full 16bit pipeline anyway.

I don't know if anyone could see the difference between an 8 bit and 16 bit output to the printer ... I suppose there may be an extremely rare image with an amazingly delicate gradation that may show a slight difference ...

But those sizes should be fine at 8 bit.  I can't print the 96" x 44" at 360 dpi at 16 bit ...



Every Mac owner I know has avoided Lion like the plague, so I can't easily try this on another version of the OS.

Interesting ... not much reason to avoid it.  It's been out for a while now, and no issues with anything other than old PPC programs that vendors decided to no longer support with the new Intel Macs (how many years has that been now?).
« Last Edit: August 31, 2012, 11:41:46 pm by Wayne Fox »
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JohnHeerema

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #8 on: August 31, 2012, 05:04:53 pm »

Quote
I can't print the 96" x 44" at 360 dpi at 16 bit ...

Thanks Wayne,

That tells me that the spool file size limit is being experienced by others too.

My own reasons for not liking Lion have more to do with the restrictive security architecture and general hand-holding than with PPC compatibility. 

Cheers,
John
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lfeagan

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #9 on: August 31, 2012, 07:40:43 pm »

My own reasons for not liking Lion have more to do with the restrictive security architecture and general hand-holding than with PPC compatibility. 

It only took me a few moments to disable the annoyances that crept in newly with Lion when I upgraded from Snow Leopard. However, I recommend holding off on moving to Mountain Lion until the service number gets to 4--which Lion is at now. I have systems on both, was originally planning on upgrading all machines to ML, but my guinea pig machined showed some issues with programs critical to my job. I still use the one machine on Mountain Lion, but not very much. It even has weird issues for me like the dock regular dying and notifications on things like email and IM receipt stop happening and launched programs never appear and cannot be Apple-Tabbed to; restarting the dock process fixes it, so I know it is dock related.
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Lance

Nikon: D700, D800E, PC-E 24mm f/3.5D ED, PC-E 45mm f/2.8D ED, PC-E 85mm f/2.8D, 50mm f/1.4G, 14-24 f/2.8G ED, 24-70 f/2.8G ED, 70-200 f/2.8G ED VR II, 400mm f/2.8G ED VR
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Wayne Fox

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #10 on: August 31, 2012, 11:44:33 pm »

It only took me a few moments to disable the annoyances that crept in newly with Lion when I upgraded from Snow Leopard. However, I recommend holding off on moving to Mountain Lion until the service number gets to 4--which Lion is at now. I have systems on both, was originally planning on upgrading all machines to ML, but my guinea pig machined showed some issues with programs critical to my job. I still use the one machine on Mountain Lion, but not very much. It even has weird issues for me like the dock regular dying and notifications on things like email and IM receipt stop happening and launched programs never appear and cannot be Apple-Tabbed to; restarting the dock process fixes it, so I know it is dock related.

I have 2 macs running on ML, and have never experienced any of those issues.  Not sure waiting until the .4 release will help you since it sounds like the issues may lie somewhere other than the OS.

However, I did a complete clean install of Lion, rather than a migration from SL, and then a reinstall of all apps.  Some of those issues you describe i did see on rare occasions with SL ... an OS that had just been updated since OS 10.3 (don't even remember what that one was ... Panther maybe?)
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John Caldwell

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #11 on: March 11, 2013, 03:52:04 pm »

Late to the party here: As I have today posted elsewhere I am running into spool size limitations when printing from LR4 and OS 10.7.5. In thinking about the factors that affect spool size and may therefore expose limitations, what do you think about:

1) Printed image dimensions and resolution - it's a linear relationship, correct? Double the number of pixels at a given bit depth, you double the volume of data being spooled?
2) 16 bit vs. 8 bit - Again a linear relationship, correct?
3) Epson driver "Fine Details" engaged
4) Epson driver "1440 vs. 2880"
5) Epson driver "Super MicroWeave" engaged
6) Epson driver "High Speed" engaged

Thank you,

John Caldwell
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John Caldwell

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Re: Maximum spool file size when using Mac/CUPS?
« Reply #12 on: March 11, 2013, 09:48:06 pm »

Answering my own query above with info gathered today from Epson regarding volume of data being spooled when sending a print job:

1) Printed image dimensions and resolution - it's a linear relationship: Double the number of pixels at a given bit depth, you double the volume of data being spooled.
2) 16 bit vs. 8 bit - Again a linear relationship; 16 bit is twice the file bulk as 8 bit, just like you were "Saving" a 16 bit file.
3) Epson driver "Fine Details" engaged increases the volume of data, but the person I talked to could not quantify the increase. This particular Epson tech allowed that, in her opinion, Fine Details could/should be eliminated as a driver choice.
4) Epson driver "1440 vs. 2880" - no impact on data mass
5) Epson driver "Super MicroWeave" engaged  - no impact on data mass
6) Epson driver "High Speed" engaged  - no impact on data mass
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