JMeter5.1基础类AbstractThreadGroup源码分析

    // Only create the map if it is required
    private final transient ConcurrentMap<TestElement, Object> children = new ConcurrentHashMap<>();

    private static final Object DUMMY = new Object();

    /** Action to be taken when a Sampler error occurs */
    public static final String ON_SAMPLE_ERROR = "ThreadGroup.on_sample_error"; // int

    /** Continue, i.e. ignore sampler errors */
    public static final String ON_SAMPLE_ERROR_CONTINUE = "continue";

    /** Start next loop for current thread if sampler error occurs */
    public static final String ON_SAMPLE_ERROR_START_NEXT_LOOP = "startnextloop";

    /** Stop current thread if sampler error occurs */
    public static final String ON_SAMPLE_ERROR_STOPTHREAD = "stopthread";

    /** Stop test (all threads) if sampler error occurs, the entire test is stopped at the end of any current samples */
    public static final String ON_SAMPLE_ERROR_STOPTEST = "stoptest";

    /** Stop test NOW (all threads) if sampler error occurs, the entire test is stopped abruptly. Any current samplers are interrupted if possible. */
    public static final String ON_SAMPLE_ERROR_STOPTEST_NOW = "stoptestnow";

    /** Number of threads in the thread group */
    public static final String NUM_THREADS = "ThreadGroup.num_threads";

    public static final String MAIN_CONTROLLER = "ThreadGroup.main_controller";

    private final AtomicInteger numberOfThreads = new AtomicInteger(0);

    public void initialize() {
        // 获取自带的LoopController类
        Controller c = getSamplerController();
        JMeterProperty property = c.getProperty(TestElement.NAME);
        property.setObjectValue(getName()); // Copy our name into that of the controller
        property.setRunningVersion(property.isRunningVersion());// otherwise name reverts
        // 初始化threadGroup自带的GenericController类（LoopController的父基类）
        c.initialize();
    }

    public Controller getSamplerController() {
        return (Controller) getProperty(MAIN_CONTROLLER).getObjectValue();
    }

    public final boolean addTestElementOnce(TestElement child){
        if (children.putIfAbsent(child, DUMMY) == null) {
            addTestElement(child);
            return true;
        }
        return false;
    }

    public void addTestElement(TestElement child) {
        getSamplerController().addTestElement(child);
    }

    public Sampler next() {
        return getSamplerController().next();
    }