48ecb80d6b
Fix StatementInvalid exception when uploading https://files.catbox.moe/vxoe2p.mp4. This was a result of multiple bugs: * First, generating thumbnails for the video failed. This was because the video uses the AV1 codec, which FFmpeg failed to decode. It failed because our version of FFmpeg was built without the `--enable-libdav1d` flag, so it uses the builtin AV1 decoder, which apparently can't handle this particular video (it spews a bunch of errors about "Failed to get pixel format" and "missing sequence header" and "failed to get reference frame"). * Because generating the thumbnails failed, an exception was raised. We tried to save the error message in the upload_media_assets.error field. However, this also failed because the error message was 77kb long (it contained the entire output of the ffmpeg command), but the `upload_media_assets` table had a btree index on the `error` column, which meant the maximum length of the error column was limited to ~2.7kb. This lead to a StatementInvalid exception being raised. * Because the StatementInvalid exception was raised while we were trying to set the upload media asset's status to `failed`, the upload was left stuck in the `processing` state rather than being set to the `failed` state. * Because the upload was stuck in the `processing` state, the upload page would hang forever waiting for the upload to complete. The fixes are to: * Build FFmpeg with `--enable-libdav1d` to use libdav1d for decoding AV1 videos instead of the builtin AV1 decoder. * Remove the index on the `upload_media_assets.error` column so that setting overly long error messages won't fail. * Catch unexpected exceptions in ProcessUploadMediaAssetJob so we can mark uploads as failed, even if `process_upload!` itself fails because it raises an unexpected exception inside its own exception handler. * Check that the video is playable with `MediaFile::Video#is_corrupt?` before allowing it to be uploaded. This way we can return a better error message if we can't generate thumbnails because the video isn't playable. This requires decoding the entire video, so it means uploads may take several seconds longer for long videos. It's also a security risk in case ffmpeg has any bugs. * Define `MediaAsset#preview!` as raising an exception on error, so it's clear that generating thumbnails can fail. Define `MediaAsset#preview` as returning nil on error for when we don't care about the cause of the error.
Jobs
This directory contains background jobs used by Danbooru. Jobs are used to handle slow-running tasks that need to run in the background, such as processing uploads or bulk update requests. They're also used for asynchronous tasks, such as sending emails, that may temporarily fail but can be automatically retried later.
Jobs use the Rails Active Job framework. Active Job is a common framework that allows jobs to be run on different job runner backends.
In the production environment, jobs are run using the Good Job backend. Jobs
are stored in the database in the good_jobs table. Worker processes spawned
by bin/good_job poll the table for new jobs to work.
In the development environment, jobs are run with an in-process thread pool. This will run jobs in the background, but will drop jobs when the server is restarted.
There is a very minimal admin dashboard for jobs at https://danbooru.donmai.us/jobs.
Danbooru also has periodic maintenance tasks that run in the background as cron jobs. These are different from the jobs in this directory. See app/logical/danbooru_maintenance.rb.
Usage
Start a pool of job workers:
RAILS_ENV=production bin/good_job start --max-threads=4
Examples
Spawn a job to be worked in the background. It will be worked as soon as a worker is available:
DeleteFavoritesJob.perform_later(user)
See also
- app/logical/danbooru_maintenance.rb
- app/controllers/jobs_controller.rb
- config/initializers/good_job.rb
- test/jobs