presto-main/src/main/java/io/prestosql/execution/SqlTaskManager.java/SqlTaskManager/start
class SqlTaskManager:    @PostConstruct
    public void start()
    {
        taskManagementExecutor.scheduleWithFixedDelay(() -> {
            try {
                removeOldTasks();
            }
            catch (Throwable e) {
                log.warn(e, "Error removing old tasks");
            }
            try {
                failAbandonedTasks();
            }
            catch (Throwable e) {
                log.warn(e, "Error canceling abandoned tasks");
            }
        }, 200, 200, TimeUnit.MILLISECONDS);

        taskManagementExecutor.scheduleWithFixedDelay(() -> {
            try {
                updateStats();
            }
            catch (Throwable e) {
                log.warn(e, "Error updating stats");
            }
        }, 0, 1, TimeUnit.SECONDS);
    }