stress apisix return 499

[kellyseeme]

Description

when Enable upstream health check，The upstream is constantly changing，In the first second it is 1 backend, in the second second it is 100 backends and in the third second it is 110，apisix Will return randomly and occasionally 499 http response code。 if Turn off health checks,then all is ok. when cap the pcap ,no error log found ，apisix No forwarding traffic to the upstream.

in access log，requst time is near 0,upstream_connect time is 0,upstream_header_time is -,response time is 0,how can i debug this issue？

Environment

• APISIX version (run apisix version):2.3.15
• Operating system (run uname -a):
• OpenResty / Nginx version (run openresty -V or nginx -V):
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info):
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):

[kellyseeme]

Turn off health checks,There will also be have 499 response code