Query Engine Graceful Shutdown

Zoomdata supports the graceful shutdown of its query engine instances. When a query engine instance is shut down, it gracefully completes queries that are in-flight and notifies clients that it is terminating.

Several query engine properties in the query-engine.properties file support graceful shutdown:

  • application.graceful.shutdown.enabled indicates whether or not graceful shutdown processing should occur. Valid values are true (perform graceful shutdown processing) or false (do not perform graceful shutdown processing). The default is true.
  • application.graceful.shutdown.event-propagation-timeout-sec specifies how long (in seconds) a query engine instance will wait to allow clients to receive the information that it is out of service. The default is 5 seconds.
  • application.graceful.shutdown.force-kill-timeout-sec specifies the maximum number of seconds that a query engine instance will wait for the number of its active tasks to reach zero. The default is 30 seconds. When this time has elapsed, all remaining active WebSockets serving in-flight queries are closed and then the query engine instance will stop.