Workers always timeout when i try to read a pdf online
#1  dcsmith2060 06-06-2019, 06:53 PM
I have many large and small pdfs I'd like to read, and I've tried reading them on server in ubuntu 16.04 and 18.04 calibre version 3.44. In all cases the pdf fails to convert and i get an error that :

Traceback (most recent call last):
File "site-packages/calibre/srv/", line 44, in run
File "site-packages/calibre/utils/ipc/", line 229, in fork_job
File "site-packages/calibre/utils/ipc/", line 107, in communicate
WorkerError: Worker appears to have hung

Is there anything I can do to help? I know a little python. Can the pdfs be prepared in the gui so that no timeout occurs? Also does the web interface for server download the whole book, or just a few pages at a time?

#2  kovidgoyal 06-06-2019, 08:58 PM
reading PDFs in the server basically converts them to EPUB under the hood. So you can preconvert them to EPUB and read that instead.

#3  dcsmith2060 06-07-2019, 12:59 AM
What happens if it's an image based pdf? I've also had poor conversion with text based pdfs with mathematics in them where the formulas aren't converted to images in the resulting epub? Would it be possible to convert the pdf to all images, kindof like a cbz? I'd be more than willing to help with the work.

#4  kovidgoyal 06-07-2019, 04:15 AM
Most browsers/devices already have PDF reading facilities, so just download and read the PDF that way. You aren't going to get good results trying to read PDFs using the calibre viewer, it is designed for reflowable documents.

#5  dcsmith2060 06-07-2019, 08:44 PM
The advantage of using a web reader is that I don't have to download the whole pdf or cbz at once and that it keeps track of what page I'm on across devices. A pdf I got from a kickstarter is over 700 meg. I've reduced it and currently read it on google play books, but am starting to investigate what it will take to degoogle my life. Google's web reader only loads a few pages at a time in the web reader, thereby limiting downloads. The whole point of having a web store is that I don't have to keep a copy of my library on my laptop.
As I said I'm a developer and if people think it's a good idea to do things this way, I'm more than happy to do some of the work.

#6  kovidgoyal 06-07-2019, 09:50 PM
You are welcome to add a PDF viewer to calibre, I have no objections. Probably base it off pdf.js. But it is not going to fit with the current viewer, which, as I said, is designed for reflowable documents.

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