Answer

The dmdebug --queues command prints information about all server queues in the system. For example:

SubscriberFE                                         [0 worker]
Current size 0, max 369; processed entries 21843
Size           0-0.00            0-0.00            0-0.00             0-0.00
Flow       21839+0.06        21803+0.05        21446+0.05         17895+0.06
Late      0.0000+0.00       0.0000+0.00       0.0000+0.00        0.0000+0.00