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Tilepic generation performance issues

Our users are experiencing performance issues when uploading images in Providence (1.7.6). The images are not all that big (+/- 2MB), but it takes upwards of 10 minutes to generate the different image files, the vast majority of that time is in generating the tilepic file. The users experience a timeout on the website, showing a a CA error message, however the GraphicsMagick calls to create the tilepic continue, and once that's done the image appears for the artifact.

I see that there's a nested for loop that is cutting the file up into 256x256 chunks and then reassembling into the .tpc file. When dealing with files of higher resolution (even as starting at 2560x2560) that process generates 100 calls to GraphicsMagick, which explains the performance issue. Some of the files the users are uploading are 11000x8500 pixels, which generates about 1400 calls to GraphicsMagick.

The options I'm seeing are:
1) Eliminate the use of Tilepics altogether for images
2) Increase the size of the tiles from 256x256 to something much larger

Are there any other options that I should be considering?

I can see in the configuration files that the default viewer and default editor for images is tilepic. What I'm wondering is:
1) Is there any major disadvantage to eliminating the tilepics? If so, what are they?
2) If there is a reason that we shouldn't eliminate tilepics, what is the consequence to increasing the tile size to something much larger? (say 1024x1024) to reduce the number of calls.


  • Try installing the PHP gmagick extension. The overhead of calling GraphicsMagick in a shell for that many tiles is making it that slow. It'll be much faster with gmagick.

    Eliminating tilepics means you can't pan-zoom on images. If this feature doesn't matter to you then you can safely remove the tilepics config. Making the tile size very large will make processing go a bit faster, but will make loading go slower. 256x256 is generally the best tile size for load performance. If you can install gmagick you'll likely find processing performance with 256x256 tiles to be acceptable.

  • Thanks Seth - that seems to be better.

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