The Ambari Metrics Collector service uses psutil to collect metrics from the host system. This is a python library used for retrieving information on running processes and system utilization. You can read more on psutil within Ambari Metrics Collector here https://github.com/apache/ambari-metrics/tree/master/ambari-metrics-host-monitoring/src/main/python/psutil. For the various Hadoop sinks, AMS uses the Hadoop sink for collection of the various hadoop components. Source code found here https://github.com/apache/ambari-metrics/blob/master/ambari-metrics-hadoop-sink/src/test/java/org/apache/hadoop/metrics2/sink/timeline/HadoopTimelineMetricsSinkTest.java. AMS uses org.apache.hadoop.metrics2.sink.timeline.cache.TimelineMetricsCache to store intermediate data until it is time to send it to HBASE. It uses the function emitMetrics to send the Metrics to Hbase whenever the specified amount of time has passed. I hope this helps you out. ... View more