presto-main/src/main/java/io/prestosql/execution/SqlQueryManager.java/SqlQueryManager/enforceCpuLimits
class SqlQueryManager:    private void enforceCpuLimits()
    {
        for (QueryExecution query : queryTracker.getAllQueries()) {
            Duration cpuTime = query.getTotalCpuTime();
            Duration sessionLimit = getQueryMaxCpuTime(query.getSession());
            Duration limit = Ordering.natural().min(maxQueryCpuTime, sessionLimit);
            if (cpuTime.compareTo(limit) > 0) {
                query.fail(new ExceededCpuLimitException(limit));
            }
        }
    }