[Okular-devel] [okular] [Bug 327846] New: PDF Render time is unreasonably slow over high latency (WAN) network connections

[Bernard Gray]

https://bugs.kde.org/show_bug.cgi?id=327846

            Bug ID: 327846
           Summary: PDF Render time is unreasonably slow over high latency
                    (WAN) network connections
    Classification: Unclassified
           Product: okular
           Version: 0.15.5
          Platform: Ubuntu Packages
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: PDF backend
          Assignee: okular-devel at kde.org
          Reporter: bernard.gray at gmail.com

Created attachment 83646
  --> https://bugs.kde.org/attachment.cgi?id=83646&action=edit
table/graph of render times of different size files opened over different
latency network connections

If I open a PDF with okular from a file share connected over a high latency WAN
connection, the render time increases to unreasonably high levels.

Eg A simple 101 page 1.9MB PDF with some text and bitmap images, takes 1 minute
to render on a connection with 30ms round trip latency.

I did my deep testing on ubuntu 12.10 (our current desktop standard) with
okular 0.15.5/poppler 0.20.4 
I did a very quick verification on ubuntu 13.10 with okular 0.17.2/poppler
0.24.1 to make sure the problem was still reproducible on a more current
release. It was.

Test bench consisted of a client running ubuntu 12.10 connected to a machine
running WANem to simulate WAN latency (no bandwidth throttling in place, only
latency was changed). 
A samba server sat on the other side of the WANem router, and the ubuntu client
connected via mount.cifs 

I opened two files from the samba share, a 1.9MB PDF with text and bitmap
pictures, and a 10KB PDF file with text. I timed the length of time to do the
"initial load" (blank pages), and the time for the final render, increasing the
latency after each set of tests from none, up to 50ms. I also timed a straight
file copy using 'time cp remotesrc localdest'. Units are in seconds unless
specified. Okular performance was set to "Greedy".
Results are in the attached spreadsheet - as you can see the render time
increases linearly with latency, in all cases the 1.9MB file is ~10x slower to
open than the 10KB file, regardless of latency.

The peak render time was 1:38s for a 1.9MB file over a connection with 50ms
latency.
Equivalent render times over the same connection:
Acrobat Reader, same 1.9MB PDF: ~6s
Okular with 1.9MB TIFF file: ~6s

In a practical sense, here's what it means for me:
The company I work for runs ~170 KDE desktops at 9 sites around Australia. Our
company file servers are located centrally at the head office. Our furthest
branch is located in Perth, and connects back to our Head Office near Griffith
NSW (~3500kms). The round trip latency to this site is ~70ms. Our lowest
latency site is Sydney, with a round trip latency of ~16ms. The other sites
range in between. 

In summary, we have larger files, and higher latency to some of our branches
than measured. Load times are already unacceptably high under my very modest
testing conditions.

What else can I do to help get this issue resolved?

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