From the Ops & Multimedia mailing lists:

We just had a brief imagescaler outage today at approx. 11:20 UTC that
was investigated and NYPL maps were found to be the cause of the outage. 

As Gergo's unanswered recent message in this thread suggested, we're actively working on a number of changes to stabilize GWToolset and improve image scaler performance in order to avoid such outages. I assumed that since everyone involved is participating in this thread, that you were waiting for these changes to happen before restarting the GWToolset job that caused the previous outage a couple of weeks ago, or that you would warn us when that job would be run again. There seems to be a communication issue here. By running this job, you've taken down thumbnail generation on Commons (and all WMF wikis) and we were lucky that someone from Ops was around, noticed it and reacted quickly. This could have been easily avoided with better coordination, by at least scheduling a time to run your next attempt, with people from Ops watching servers at the time the job is run. Please make sure that this happens for the next batch of NYPL maps/massive files that you plan to upload with GWToolset. All it takes is scheduling a day and time for the next upload attempt.

Gergo and I will keep replying to this thread to notify everyone when our related code changes are merged.


On Wed, May 7, 2014 at 10:26 PM, Gergo Tisza <gtisza@wikimedia.org> wrote:
Uhh... let's give this another shot in the morning.

I went through last day's upload logs; on average there are ~600 uploads an hour, the peak was 1900, the negative peak around 240. (The numbers are at http://pastebin.com/raw.php?i=wmBRJm1G in case anybody finds them useful.) So that's around 4 files per minute in worst case.

If we are aiming for no more than 10% of Special:NewFiles to be taken up by GWToolset, that means 5 uploads per run of the control job (10% of the 50 slots at Special:NewFiles) - the upload jobs can't really be throttled, so we must make sure they come in small enough chunks, no matter how much delay there is between the chunks). Also, we want to keep below 10% of the total Commons upload rate - that means 24 images per hour, which is roughly five runs of the control job per hour.

So the correct config is

GWToolset\Config::$mediafile_job_throttle_default = 5;
$wgJobBackoffThrottling['gwtoolsetUploadMetadataJob'] = 5 / 3600;

I'm leaving the max throttle at 20 so that people who are uploading small, non-TIFF images can get a somewhat higher speed.