nginx abort connection during reload when proxy_cache enabled

[Wenjun]

We use nginx as the cluster ingress provider, and hit the case when:
 1. enabled proxy_cache, and the specific cache is expired
 2. nginx is reloading config
then for incoming request, the backend servers can still receive the request and send back response to nginx, while client will receive "curl: (52) Empty reply from server".


It seems nginx reload may cause the connection break?


attached debug log below:
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