CODEWITHSUNDEEP
linuxmultithreadingpdfghostscript
Perb
Perb

Reputation: 31

Ghostscript Combine PDfs and Multithread/Core

)

I know there are a couple of questions and threads out about similar stuff but none would work for me. I'm trying to combine ~1000 pdf files in one. I tried a couple tools but only gs (ghostscript) does a proper compression. My problem is that is that multi threads are not working/ I've got 24cores and like to use e.g. 8 for the task, but top shows me that it uses still only one. My command:

gs -q -dNOPAUSE -dNOPROMPT -q -dBATCH -dNumRenderingThreads=8 -dBandHeight=100 -dBandBufferSpace=500000000 -sBandListStorage=memory -dBufferSpace=1000000000 -sDEVICE=pdfwrite -sOutputFile=combined_gs.pdf sourcefiles/*.pdf

I have to speed up this a bit as it takes round about 60 seconds and I need this on the fly. Any suggestions?

Upvotes: 3

Views: 2504

Answers (1)

KenS
KenS

Reputation: 31159

The pdfwrite device doesn't use threading (it would be difficult for it to do so). The clue is in the name 'NumRenderingThreads', pdfwrite doesn't render.

Since it isn't rendering BandHeight, BandBufferSpace, BandListStorage and BufferSpace will also have no effect. (You've also specified -q twice)

Please be aware that Ghostscript and the pdfwrite device do not 'manipulate' PDF input, not combine, concatenate or anything similar. What it does is interpret all the input, creating a set of graphic primitives, these primitives are then re-assembled into a brand new PDF output file. The new output file has nothing in common with any of the inputs, and our goal in this is that the visual appearance should be the same. While we do handle a number of non-makring objects from the input these are of secondary importance.

As will be obvious, this is a much more complex process than treating the contents of a PDF file as a series of building blocks which can be rearranged, which is why its slower. To be honest reading, interpreting, rewriting 1000 files in 1 minute seems pretty fast to me.

Upvotes: 11

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