To clear (zero) the counters in a node-specific, in-memory
    cache, issue the COUNTERS CLEAR command on that particular node.
    The command creates the node-specific, in-memory section of
    association and channel counters if it does not already exist.
    Then it zeros all fields in the in-memory section. Note that the
    counters will be zeroed without first merging their values into
    the cluster-wide database of channel counters. If a cluster-
    wide, on-disk database does not already exist, a new one will be
    created. Finally, the fields in the on-disk database for numbers
    of stored messages, message recipients, and message volumes are
    set based on the entries in the PMDF queue cache database.

    Either the association counters, or channel counters, or both,
    may be cleared. The default is to clear both association and
    channel counters.

    If you want to update the on-disk database with the old in-memory
    values before clearing them, then you should issue a COUNTERS
    SYNCHRONIZE command before issuing the COUNTERS CLEAR command.