The new parameter is named SendQueueLimit which is not supported by puppet-collectd at the moment.
https://github.com/voxpupuli/puppet-collectd/pull/950
I have added ExtraConfig: collectd::plugin::amqp1::send_queue_limit: 40 Stopped STF server and observed that collecct memory stays stable and not goes up.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (Red Hat OpenStack Platform 16.1 bug fix and enhancement advisory), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHEA-2020:4284