latency statistic data is empty

[wannastar]

step1:
compile fastdds with -DFASTDDS_STATISTICS=ON（default is on）and -DPERFORMANCE_TESTS=ON
step2:
./LatencyTest publisher -f payloads_demands.csv --domain 0 -s 1000000
./LatencyTest subscriber -f payloads_demands.csv --domain 0
step3:
configure fastddsmonitor to introspect FASTDDS LATENCY like picture1, but the graph is always empty.

[rsanchez15]

Hi @wannastar

As you mentioned, FASTDDS_STATISTICS is set to ON by default in latest versions of Fast DDS. However, this does not imply that the internal statistics are enabled, as you should explicitly enable each specific statistic you want your application to report. Here you have the link to the documentation explaining how to do so.

For this case, my recommendation is to do it via environment variable. On each terminal running a Fast DDS application, just run the following command:

export FASTDDS_STATISTICS="HISTORY_LATENCY_TOPIC;NETWORK_LATENCY_TOPIC;PUBLICATION_THROUGHPUT_TOPIC;SUBSCRIPTION_THROUGHPUT_TOPIC;RTPS_SENT_TOPIC;RTPS_LOST_TOPIC;HEARTBEAT_COUNT_TOPIC;ACKNACK_COUNT_TOPIC;NACKFRAG_COUNT_TOPIC;GAP_COUNT_TOPIC;DATA_COUNT_TOPIC;RESENT_DATAS_TOPIC;SAMPLE_DATAS_TOPIC;PDP_PACKETS_TOPIC;EDP_PACKETS_TOPIC;DISCOVERY_TOPIC;PHYSICAL_DATA_TOPIC"

This will enable all the statistics in Fast DDS applications. In case you want to report just the latency statistic, run this other command:

export FASTDDS_STATISTICS="HISTORY_LATENCY_TOPIC"

[wannastar]

yes, i had already stated this variable in ~/.bashrc like this. i can lookup the participant info by fastddsspy link pictur2, so there is the statisctic info datawriter.

[wannastar]

but it is still empty.

[wannastar]

DDSHelloworldExample demo can get statistic data, but LatencyTest demo could not. you can have a try.