During regression testing undertaken to diagnose a separate problem, the configuration file of an 8-node cluster comprising 6 DataServers and 1 ClientServer, each normally on a dedicated host, was modified to run all services on the one host.
It is accepted that the above is not a practical 'real world' configuration. However it was justified because a) it was part of a regression test, and b) previous SPARQL compliance testing had been run in a similar configuration, albeit with only 2 DataServer instances rather than 6.
It was found that numerous errors and warnings were written to the logs when running this '6 DataServer on one host' configuration. The configuration was further modified to restrict the number of DataServer instances to 2, matching the SPARQL compliance configuration mentioned. In this case no errors were written to the error log file.
As mentioned, this is not a practical 'real world' configuration, however it is possible that the observed behaviour is highlighting a condition that may affect 'real world' configurations under certain conditions of load.
Log files are attached