Hi Team,

I had created the issue in google groups https://groups.google.com/forum/#!topic/node-mongodb-native/egQXozY8D7M.

1 Primary and 2 secondary servers.

The issue we faced on our servers(Public facing) where connections on our MongoDB(Version: 3.4.x) were increased so much that our application went down. We are using driver version 2.x on our producion system. The system automatically recovered after ~20 minutes, where the connections were restored at count where it was earlier.

In google group we got reply  to try using driver version 3.x, and we tried that today on our testing server with driver version 3.2.5 but the issue seems to be still reproducible. 

Following steps are causing too many connections issue

• Create connection with MongoDB in replicaset.(Read/Write - PrimaryPreferred/majority).
• Disconnect primary so that application won't be able to talk to Primary machine.
• After couple of minutes if we make Primary server available.
• After the last steps observe that the no. of connections are too many.
• And this connections are not getting ended over time as well and other actual new connections still are not getting created due to these unwanted connections.

Thanks,