[poppler] Poppler too slow when compiled with cms

[Koji Otani]

From: Albert Astals Cid <aacid at kde.org>
Subject: Re: [poppler] Poppler too slow when compiled with cms
Date: Sun, 18 Jan 2009 20:25:03 +0100
Message-ID: <200901182025.03909.aacid at kde.org>

aacid> A Diumenge 18 Gener 2009, Carlos Garcia Campos va escriure:
aacid> > when compiled with cms support enabled poppler is too slow when
aacid> > rendering some pages. For example, rendering page 831 of PDF
aacid> > Specification 1.7 takes more than 1 minute in my system.
aacid> >
aacid> > Koji, any idea why does it happen?
aacid> 
aacid> I think the problem is that in this page there's a Pattern, our slowest code, 
aacid> that forces the creation of 272 GfxICCBasedColorSpaces that isn't fast 
aacid> either, but the problem is not the GfxICCBasedColorSpaces itself, the problem 
aacid> is that the pattern implementation sucks.
aacid> 
aacid> To try to bypass this problem we could try implement a kind of cache for 
aacid> GfxColorSpace so you don't have to recreate one if is the same as one of the 
aacid> last N (1-5). This has several implications, like adding refcounting to 
aacid> GfxColorSpace and finding how to know if we are asked for the same 
aacid> GfxColorSpace.
aacid> 

I think you are right.
I did quick hack to test only this case. It caches
 a last GfxICCBasedColorSpace.

  It created only 3 GfxICCBasedColorSpaces for rendering the page.
  It took 2 seconds. (before hack, it took 140 seconds)

-----------------
Koji Otani

aacid> Also sometime somewhen we need someone to sit down and kill the Pattern 
aacid> bottleneck.
aacid> 
aacid> This is going to take probably some time that goes against Carlos' 
aacid> idea/need/will to release a new stable version based on master "soon".
aacid> 
aacid> So options:
aacid>  * I'm wrong and this is not the cause of the slowdown
aacid>  * Someone else has a better idea how to fix this
aacid>  * We wait for the solution to land in master and probably release later this 
aacid> year (my initial intention)
aacid>  * We remove Color Management from master and do a master release soon 
aacid> 
aacid> I would vote for 3 as color management seems a nice thing to have imho and 
aacid> it's been just 3 months since latest major release.
aacid> 
aacid> What are other's opinions here?
aacid> 
aacid> Albert
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