502 ERROR "no live upstreams while connecting to upstream" with keepalive

[zhongcy]

trafficstars

I use keepalive with jdomain:

` keepalive_timeout 65; keepalive_requests 100;

upstream jdomain-upstream {jdomain test.my.com port=443 interval=60; keepalive 8;}`

but some time, requests get 502 "no live upstreams while connecting to upstream" error .