connPoolStats — MongoDB Manual https://docs.mongodb.com/manual/reference/command/connPoolStats/
connPoolStats
The command connPoolStats returns information regarding the open outgoing connections from the current database instance to other members of the sharded cluster or replica set.
mongodb.connections.current Per Second MongoDB Current Session 当前会话达到限制
stack=server selection error: server selection timeout, current topology: { Type: Unknown, Servers: [{ Addr: dds-xxx-pub.mongodb.rds.aliyuncs.com:3717, Type: Unknown, Average RTT: 0, Last error: connection() error occured during connection handshake: connection(dds-xxx-pub.mongodb.rds.aliyuncs.com:3717[-122]) socket was unexpectedly closed: EOF }, ] }
连接统计connections
统计连接到当前数据库实例的连接，这个值可能比真实的业务视角来的略大一些，因为它还包含节点之间用以维持心跳、选举、同步oplog等等的连接