Restricting Correlator Resource Usage with Control Groups

On Linux platforms, control groups (cgroups) can be used to limit the resource usage of processes, for example, by limiting the number of CPUs a process can detect. Apama uses the number of CPUs to determine how many threads to create. So you can use cgroups to limit this.

All cgroup restrictions that are currently active are logged at startup by the correlator (see also Starting the correlator).

The number of CPUs and memory available to the correlator are exposed through various means under the labels physicalCores and availableMemoryMB:

• Management interface. See also Using the Management interface.
• Apama’s REST API. See also Managing and monitoring over REST.
• Prometheus (under the metric sag_apama_correlator_metadata). See also Monitoring with Prometheus.