presto-main/src/main/java/io/prestosql/server/CoordinatorModule.java/CoordinatorModule/createTransactionIdleCheckExecutor
class CoordinatorModule:    @Provides
    @Singleton
    @ForTransactionManager
    public static ScheduledExecutorService createTransactionIdleCheckExecutor()
    {
        return newSingleThreadScheduledExecutor(daemonThreadsNamed("transaction-idle-check"));
    }