Note on connection limit in version 6.5.0

The following note in https://docs.couchbase.com/c-sdk/2.10/managing-connections.html#handle-lifetime:

> Each Couchbase Data node allows up to 30,000 concurrent key-value connections by default, in Couchbase Data Platform 6.0 and earlier. From 6.5 onwards, the default value is 65,000.

is misleading for customers.

As per https://issues.couchbase.com/browse/MB-32704 , instead of a per-port limit on the number of connections we are merging the number of connections for ports 11210, 11209 and 11207 to a single number. For example:

Prior to version 6.5:

Connection limit on 11210 : 30,000
Connection limit on 11207 : 30,000
Connection limit on 11209 : 5,000

Hence, if an application is using only non-SSL connections those 30,000 file descriptors binded to port 11207 will be unused and memcached will start rejecting connections after 30,000.

—

Version 6.5 and above:

Connection limit on 11210 and 11207 : 60,000
Connection limit on 11209 : 5,000

Here, (connections on 11210) + (connections to 11207) = 60,000 . (connections on 11210) can be 60,000 and (connections on 11207) can be 0.

Improvement : Number of available file descriptors for applications which use only SSL or applications using only non-SSL is increased to 60K.

The documentation can be misleading in the sense that customers can understand the statement as follows:

Connection limit on 11210 : 65,000
Connection limit on 11207 : 65,000
Connection limit on 11209 : 5,000