Change Details

Right now when a large pdf / multipage tiff file is uploaded, `LocalFile::prerenderThumbnail` generates a large number of jobs, equal to the number of pages multiplied by the size of `MainConfigNames::UploadThumbnailRenderMap`. This means that in production, where that array has size 4, a 1000 pages pdf generates 4000 prerender jobs, all of which will have to extract a single page from this huge pdf, a quite expensive operation that regularly overloads our thumbnailing infrastructure. I also don't see a huge advantage in generating so many thumbnails. I would propose to modify the mechanism so that we pregenerate the thumbnails only for the first N pages of any document exceeding M pages, with N and M being configuration parameters.

Right now when a large pdf / multipage tiff file is uploaded, `LocalFile::prerenderThumbnail` generates a large number of jobs, equal to the number of pages multiplied by the size of `wgUploadThumbnailRenderMap`. This means that in production, where that array has size 4, a 1000 pages pdf generates 4000 prerender jobs, all of which will have to extract a single page from this huge pdf, a quite expensive operation that regularly overloads our thumbnailing infrastructure. I also don't see a huge advantage in generating so many thumbnails. I would propose to modify the mechanism so that we pregenerate the thumbnails only for the first N pages of any document exceeding M pages, with N and M being configuration parameters.

Right now when a large pdf / multipage tiff file is uploaded, `LocalFile::prerenderThumbnail` generates a large number of jobs, equal to the number of pages multiplied by the size of `MainConfigNames::`wgUploadThumbnailRenderMap`. This means that in production, where that array has size 4, a 1000 pages pdf generates 4000 prerender jobs, all of which will have to extract a single page from this huge pdf, a quite expensive operation that regularly overloads our thumbnailing infrastructure. I also don't see a huge advantage in generating so many thumbnails. I would propose to modify the mechanism so that we pregenerate the thumbnails only for the first N pages of any document exceeding M pages, with N and M being configuration parameters.