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Uncacheable RecentChanges feed, outlier in frontend cache misses
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Description

On text Varnishes the misses list shows this URL:
/w/api.php?hidebots=1&days=7&limit=50&hidewikidata=1&action=feedrecentchanges&feedformat=atom
as an outlier, with receiving approx 1700 req/min right now. For reference, the second on that list (also an outlier, probably a bug) is receiving 70 req/min.

From the headers, I see that it's all Cache-Control: private, expires immediately.

I have no data on when this began and it could be old, but I don't remember seeing it before. From the git logs I see commit I06ee0f01d896bc66545a1800b24693ce7524e433 (ChangesListSpecialPage: Separate all functionality for generating feeds) that changed some feed internals and URLs, so perhaps this is related?


Version: unspecified
Severity: normal

Details

Reference
bz63249

Event Timeline

bzimport raised the priority of this task from to Unbreak Now!.
bzimport set Reference to bz63249.
bzimport added a subscriber: Unknown Object (MLST).
faidon created this task.Mar 29 2014, 2:45 AM

I have no data on when this began and it could be old, but I don't remember
seeing it before. From the git logs I see commit
I06ee0f01d896bc66545a1800b24693ce7524e433 (ChangesListSpecialPage: Separate
all functionality for generating feeds) that changed some feed internals and
URLs, so perhaps this is related?

Yes, it appears that change disabled varnish cache, where previously it was set to cache in varnish for 10 seconds. Given the amount of hits that page gets, even a 10 second cache is probably helpful.

Change 121912 had a related patch set uploaded by Brian Wolff:
Cache RecentChanges Atom feed in varnish for 15 seconds

https://gerrit.wikimedia.org/r/121912

Change 121912 merged by jenkins-bot:
Cache RecentChanges Atom feed in varnish for 15 seconds

https://gerrit.wikimedia.org/r/121912

Change 125714 had a related patch set uploaded by Reedy:
Cache RecentChanges Atom feed in varnish for 15 seconds

https://gerrit.wikimedia.org/r/125714

Change 125716 had a related patch set uploaded by Reedy:
Cache RecentChanges Atom feed in varnish for 15 seconds

https://gerrit.wikimedia.org/r/125716

Change 125714 merged by Reedy:
Cache RecentChanges Atom feed in varnish for 15 seconds

https://gerrit.wikimedia.org/r/125714

Change 125716 merged by Reedy:
Cache RecentChanges Atom feed in varnish for 15 seconds

https://gerrit.wikimedia.org/r/125716