}
@Override
protected synchronized void serviceInit(Configuration conf)
throws Exception {
appHistoryServer = new ApplicationHistoryServer();
conf.setClass(YarnConfiguration.APPLICATION_HISTORY_STORE,
MemoryApplicationHistoryStore.class, ApplicationHistoryStore.class);
conf.setClass(YarnConfiguration.TIMELINE_SERVICE_STORE,
MemoryTimelineStore.class, TimelineStore.class);
appHistoryServer.init(conf);