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(Updated June 16, 2016, 6:43 p.m.) Review request for Ambari, Andrew Onischuk, Laszlo Puskas, Robert Levas, Sandor Magyari, and Sumit Mohanty. Changes ------- 1. Introduced ambari agent config properties (ambari-agent.ini) for a minimum and maximum heartbeat internals 2. The computed heartbeat intervals is used all the time not just when there are still pending tasks(stages) Bugs: AMBARI-17248 https://issues.apache.org/jira/browse/AMBARI-17248 Repository: ambari Description ------- Commands to be executed by ambari-agents are being sent down by the server in the response message to agent heartbeat messages. The server processes the received heartbeat, it checks if there are next commands scheduled to be executed by ambari-agent and adds those to the heartbeat response for the ambari-agent. The server organises the commands that can be executed in parallel into stages. Ambari server ensures that only the commands of a single stage is scheduled to be executed by the agent and starts scheduling the commands of the next stage only after all commands of current stage has finished successfully. The processing of command status received with the heartbeat message happens asynchronously to heartbeat response in HeartBeatProcessor and ActionScheduler creation thus when the heartbeat response is created the commands for the next stage are not scheduled yet. This means that the next commands will be sent to agent only with the next heartbeat. Agents currently sends a heartbeat to the server on command a completion or at a timeout = self.netutil.HEARTBEAT_IDDLE_INTERVAL_SEC – self.netutil.MINIMUM_INTERVAL_BETWEEN_HEARTBEATS interval which is ~10 seconds if there are no commands to be executed. This means that when the server receives a heartbeat triggered by the completion of the last command from the current stage the server will send the commands for the next stage only 10 seconds later when the next heartbeat is received. This leads to agents spending considerable amount of time idle when there are multiple stages to be executed. Agents should heartbeat at a higher rate while there are still pending stages to be executed. Diffs (updated) ----- ambari-agent/conf/unix/ambari-agent.ini 8f2ab1b ambari-agent/conf/windows/ambari-agent.ini df88be6 ambari-agent/src/main/python/ambari_agent/AmbariConfig.py 89a881a ambari-agent/src/main/python/ambari_agent/Controller.py e981a76 ambari-agent/src/main/python/ambari_agent/NetUtil.py 80bf3ae ambari-agent/src/test/python/ambari_agent/TestNetUtil.py d72e319 ambari-agent/src/test/python/ambari_agent/examples/ControllerTester.py 8103872 ambari-server/src/main/java/org/apache/ambari/server/agent/HeartBeatHandler.java 35a37e3 ambari-server/src/main/java/org/apache/ambari/server/agent/HeartBeatResponse.java 1ab7ae9 ambari-server/src/main/java/org/apache/ambari/server/state/Cluster.java ac0ddd2 ambari-server/src/main/java/org/apache/ambari/server/state/Clusters.java bd9de13 ambari-server/src/main/java/org/apache/ambari/server/state/cluster/ClusterImpl.java 3d2388e ambari-server/src/main/java/org/apache/ambari/server/state/cluster/ClustersImpl.java c26e1e9 ambari-server/src/test/java/org/apache/ambari/server/state/cluster/ClusterImplTest.java 627ade9 Diff: https://reviews.apache.org/r/48722/diff/ Testing ------- Manual testing. Unit tests in succeeded. Thanks, Sebastian Toader