Is a reference to Connections that is stored in Pool. This is an intermediate object that is outside of the circular reference loop of com.sun.jndi.ldap.Connection <-> com.sun.jndi.ldap.LdapClient <-> com.sun.jndi.ldap.pool.Connections Because Connection is a daemon thread, it will keep LdapClient alive until LdapClient closes Connection. This will in turn keep Connections alive. So even when Connections is removed from (the WeakHashMap of) Pool, it won't be finalized. ConnectionsRef acts as Connections's finalizer. Without connection pooling, com.sun.jndi.ldap.LdapCtx's finalize() closes LdapClient, which in turn closes Connection. With connection pooling, ConnectionsRef's finalize() calls Connections.close(), which in turn will close all idle connections and mark Connections such that in-use connections will be closed when they are returned to the pool.