question: private void checkEngineStates ( ) { try { for ( String engine : dataManager . getChildren ( BASE_PATH ) ) { Long lastHeartBeat = getHeartBeat ( engine ) ; if ( lastHeartBeat != null ) { long age = System . currentTimeMillis ( ) - lastHeartBeat ; if ( age >= MAX_AGE ) { removeEngineState ( engine ) ; } } } } catch ( Exception e ) { log . error ( "Error checking Engine States" , e ) ; } }
target:  Checks the state of all registered engines, killing any which are no longer alive.