def _run_tests(self, test_queue, setup_flag, teardown_flag):
    """Start a thread for each Job instance and block until all of the tests are run.
    Returns a (combined report, user interrupted) pair, where the
    report contains the status and timing information of tests run
    by all of the threads.
    """

    threads = []
    interrupt_flag = threading.Event()
    user_interrupted = False
    try:
        # Run each Job instance in its own thread.
        for job in self._jobs:
            thr = threading.Thread(
                target=job, args=(test_queue, interrupt_flag), kwargs=dict(
                    setup_flag=setup_flag, teardown_flag=teardown_flag))
            # Do not wait for tests to finish executing if interrupted by the user.
            thr.daemon = True
            thr.start()
            threads.append(thr)
            # SERVER-24729 Need to stagger when jobs start to reduce I/O load if there
            # are many of them.  Both the 5 and the 10 are arbitrary.
            # Currently only enabled on Evergreen.
            if _config.STAGGER_JOBS and len(threads) >= 5:
                time.sleep(10)

        joined = False
        while not joined:
            # Need to pass a timeout to join() so that KeyboardInterrupt exceptions
            # are propagated.
            joined = test_queue.join(TestSuiteExecutor._TIMEOUT)
    except (KeyboardInterrupt, SystemExit):
        interrupt_flag.set()
        user_interrupted = True
    else:
        # Only wait for all the Job instances if not interrupted by the user.
        self.logger.debug("Waiting for threads to complete")
        for thr in threads:
            thr.join()
        self.logger.debug("Threads are completed!")