While working on T223310, I noticed the following increase in GET ops registered by mcrouter on appservers:
On apis is not that heavy but still present:
From the memcached metrics
I don't see the same increase, and if I break down the graph by mc host, I cannot see anything either it is difficult to spot the same increase since memcached aggregates get+gets calls in the same metric (gets in our case are a disproportionate amount compared to get).
If I break down the above mcrouter graphs by mw instance I can see that most of the appservers started to make more GET requests, not only few ones.
The only noticeable thing that I can see from the SAL is @jijiki increasing to 5% the percentage of traffic served by PHP7: https://tools.wmflabs.org/sal/log/AWp3wVrdOwpQ-3Pkw6oo
Zoom showing two bumps:
We know for sure that the increase is related to php7, but we still don't know why.