Current Behavior

如果打开了prometheus插件，并且upstream使用了k8s服务发现或者upstream ip随着发布而改变的话，在apisix中就会产生过多的监控key，从而导致内存不断增长，如果不重启apisix最终OOM

Expected Behavior

我期望在upstream ip改变的时候有一个自动检测机制，把内存里的监控指标中不存在的node节点的key进行释放

Error Logs

No response

Steps to Reproduce

我通过将指标中的node纬度关闭从而规避了因发布而导致的upstream ip 改变产生过多key的问题

Environment

• APISIX version (run apisix version):
• 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):