Too much TIME_WAIT connections on backends after 2.1.5 upgrade

[andan andan]

Hi.

This morning, we have upgraded to 2.1.5 (from 2.1.4) and now we have
too much TIME_WAIT connections on backends.

Before the upgrade on one backend we can saw over 90 TIME_WAIT
connections and just after the
upgrade the TIME_WAIT connections goes to more than 400 and several
hours after, the number is stable.

This is not an issue perse, we can reduce the TIME_WAIT connections
tunning several kernel parameters, but I'm curious about this new
behaviour.

Thanks.
Kind Regards.