Performances

Maximum Message Input Rate

A single device in a C++ device server can receive 4 kHz of small messages (Hash containing a single INT32) without substantial latencies, measured as the delays between when a message is sent and when it is received.

The following images show the received message rates (on the left, averaged over periods of 10 s) and the latencies (on the right, averaged over 5 s) of a test running for more than 30 hours using Karabo 2.11.0 [1]. Upper images plot the measured rates and latencies versus time whereas the lower image show their histograms.

The reduction of very few outliers after about half of the test period is likely due to a change of the overall system load (network, CPU, …).

Further tests exhibit that rates up to 10 kHz do not cause problems when reached for several minutes. If the high rate continues, the message receival rate drops suddenly and a backlog of messages on the broker arises.

Footnotes

[1]	Older releases had a limit slightly above 2 kHz.