[PDFBOX-5852] Hi CPU and memory usage when converting a PDF with type 4 shading

• Type: Wish
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.28
• Fix Version/s: 2.0.33, 3.0.3 PDFBox, 4.0.0
• Component/s: Rendering
• Assignee: Andreas Lehmkühler
• Reporter: Larry Lynn
• Created: 22/Jul/24 22:04
• Updated: 26/Sep/24 06:20
• Resolved: 26/Sep/24 06:20

Description

We've observed excessive CPU and memory consumption when converting a PDF to images when the PDF contains type 4 shading.  This is especially noticeable when the conversion is done with a high DPI.  Can this be improved?

 

Conversation from the PDFBox users mailing list follows

Initial email:

Hi CPU and memory usage when converting a PDF with type 4 shadingHello PDFBox users and maintainers,

We have a PDF that causes performance problems when we use PDFBox to
convert it to an image with renderImageWithDPI(). We're calling
renderImageWithDPI()
with 650 DPI. I realize this is a very high value - we're using it for
high fidelity original images that will later be downsampled. On my work
laptop which has fairly strong hardware, the conversion takes 25 minutes
and consumes 20GB of memory. CPU and memory usage is reduced if we use a
lower DPI.

The PDF is 1 page long. It contains type 4 shading / Gouraud free form
triangle meshes. We've been aware of some performance issues with type 4
shading for a little while now, but the PDFs that contained the type 4
shading belonged to our customers and we were not authorized to share
them. We finally found a problem input document that is non-sensitive and
that we are authorized to share. I've attached a copy of the problem PDF
to this email.

I searched the archives for the users and the developers mailing list and I
didn't find anything specifically about this issue.
I searched through the PDFBox jira tickets and I found a couple of tickets
that looked similar: PDFBOX-2901 & PDFBOX-4491. PDFBOX-2901 seems to most
closely describe what we're seeing, but that was closed in PDFBox 2.0.0,
and our issue still reproduces with PDFBox 2.0.28.

Should I refer this issue over to the developers mailing list or create a
PDFBox Jira ticket for this?

Thanks and Regards,
Larry Lynn

Response:

Hi,

Yes shading can be very slow, especially at high dpi. The attachment
didn't get through, please upload to a sharehoster or create a ticket.
If you need to register then add a meaningful text, e.g. the subject of
this post so we know you're not a spammer. Also retry with 2.0.31 and
3.0.2 just to be sure. However I'm pessimistic that this can be fixed.

Tilman