Programming with JMeter-- JMeterThread
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2022-04-30 08:45:52
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到上一篇ThreadGroup为止,基本上在项目中可以完成对JMeterEngine / ThreadGroup 的整合,现在要来分析下JMeterThread,以便更好的集成到项目中。
一个 JMeterThread 好比一个vu(虚拟用户),他的创建和启动已经在ThreadGroup这一篇中完整的分析,我们是将JMeterThread委托给一个叫做DaemonizableNamedRunnable(这是因为我需要整合 weblogic workmanager 统一管理线程池)的实例来运行的, 附DaemonizableNamedRunnable代码
//remote case runnable = new DaemonizableNamedRunnable() { @Override public String getName() { return jmThread.getThreadName(); } @Override public boolean isDaemon() { return true; } @Override public void release() { } @Override public void run() { Security.runAs(subj, new PrivilegedAction<Void>() { @Override public Void run() { jmThread.run(); return null; } }); } }; //Local Case runnable = new DaemonizableNamedRunnable() { @Override public String getName() { return jmThread.getThreadName(); } @Override public boolean isDaemon() { return true; } @Override public void release() { } @Override public void run() { jmThread.run(); } };
也就是说外围的一些工作都在ThreadGroup里完成了, 现在看看其内部的结构,首先看下大概的类图(不全,JMeterEngine没有画进去):
结合初始化创建代码:
//ThreadGroup创建JMeterThread private CustomJMeterThread makeThread(int groupCount, ListenerNotifier notifier, ListedHashTree threadGroupTree, StandardJMeterEngine engine, int i, JMeterContext context) { // N.B. Context needs to be fetched in the correct thread boolean onErrorStopTest = getOnErrorStopTest(); boolean onErrorStopTestNow = getOnErrorStopTestNow(); boolean onErrorStopThread = getOnErrorStopThread(); boolean onErrorStartNextLoop = getOnErrorStartNextLoop(); String groupName = getName(); final CustomJMeterThread jmeterThread = new CustomJMeterThread(cloneTree(threadGroupTree), this, notifier); jmeterThread.setThreadNum(i); jmeterThread.setThreadGroup(this);//持有线程所属的 ThreadGroup 实例 jmeterThread.setInitialContext(context); final String threadName = groupName + " " + groupCount + "-" + (i + 1); jmeterThread.setThreadName(threadName); jmeterThread.setEngine(engine); //持有一个 当前运行的 JMeterEngine 实例,这个以后会有用 jmeterThread.setOnErrorStopTest(onErrorStopTest); jmeterThread.setOnErrorStopTestNow(onErrorStopTestNow); jmeterThread.setOnErrorStopThread(onErrorStopThread); jmeterThread.setOnErrorStartNextLoop(onErrorStartNextLoop); return jmeterThread; } //JMeterThread 构造方法 public JMeterThread(HashTree test, JMeterThreadMonitor monitor, ListenerNotifier note) { this.monitor = monitor; threadVars = new JMeterVariables(); testTree = test; compiler = new TestCompiler(testTree); controller = (Controller) testTree.getArray()[0]; SearchByClass<TestIterationListener> threadListenerSearcher = new SearchByClass<TestIterationListener>(TestIterationListener.class); // TL - IS test.traverse(threadListenerSearcher); testIterationStartListeners = threadListenerSearcher.getSearchResults(); notifier = note; running = true; } //JMeterThread保存线程上下文变量 public void setInitialContext(JMeterContext context) { threadVars.putAll(context.getVariables()); }
非常清晰了,JMeterThread的创建和初始化基本上针对以下几点:
1) onError 设置,方便在出错时响应
2) 设置线程所在的ThreadGroup 和 JMeterEngine
3) 保存好上下文到 线程 Local 的 JMeterVariables
4) 保存好测试数据结构 HashTree, 解析出controller, listener. 之前我们提到过JMeter 提供了注入 LoopController / Runtime 来控制线程的循环,和注入ResultCollector之类的Listener来收集测试结果。
初始化完毕,我们再来看运行过程,即run()方法:
@Override public void run() { // threadContext is not thread-safe, so keep within thread JMeterContext threadContext = JMeterContextService.getContext(); LoopIterationListener iterationListener=null; try { iterationListener = initRun(threadContext); while (running) { Sampler sam = controller.next(); while (running && sam != null) { process_sampler(sam, null, threadContext); threadContext.cleanAfterSample(); if(onErrorStartNextLoop || threadContext.isRestartNextLoop()) { if(threadContext.isRestartNextLoop()) { triggerEndOfLoopOnParentControllers(sam, threadContext); sam = null; threadContext.getVariables().put(LAST_SAMPLE_OK, TRUE); threadContext.setRestartNextLoop(false); } else { boolean lastSampleFailed = !TRUE.equals(threadContext.getVariables().get(LAST_SAMPLE_OK)); if(lastSampleFailed) { if(log.isDebugEnabled()) { log.debug("StartNextLoop option is on, Last sample failed, starting next loop"); } triggerEndOfLoopOnParentControllers(sam, threadContext); sam = null; threadContext.getVariables().put(LAST_SAMPLE_OK, TRUE); } else { sam = controller.next(); } } } else { sam = controller.next(); } } if (controller.isDone()) { running = false; } } } // Might be found by contoller.next() catch (JMeterStopTestException e) { log.info("Stopping Test: " + e.toString()); stopTest(); } catch (JMeterStopTestNowException e) { log.info("Stopping Test Now: " + e.toString()); stopTestNow(); } catch (JMeterStopThreadException e) { log.info("Stop Thread seen: " + e.toString()); } catch (Exception e) { log.error("Test failed!", e); } catch (ThreadDeath e) { throw e; // Must not ignore this one } catch (Error e) {// Make sure errors are output to the log file log.error("Test failed!", e); } finally { currentSampler = null; // prevent any further interrupts try { interruptLock.lock(); // make sure current interrupt is finished, prevent another starting yet threadContext.clear(); log.info("Thread finished: " + threadName); threadFinished(iterationListener); monitor.threadFinished(this); // Tell the monitor we are done JMeterContextService.removeContext(); // Remove the ThreadLocal entry } finally { interruptLock.unlock(); // Allow any pending interrupt to complete (OK because currentSampler == null) } } }
代码结构很清晰:
1) initRun(代码省略):
初始化Thread Context (主要是初始化好当前 Thread / threadgroup / engine 实例, 线程上下文变量, 线程数,线程循环控制器,监听器),
执行 线程正式运行前的delay(若有thread rampup 策略的话)工作
Thread计数,numberOfActiveThreads / numberOfThreadsStarted / numberOfThreads
2)循环运行,直到 running 为 false(一般manually 停止测试就必须会设置该flag为false) OR controller.next()为null,也就是说配置的循环控制器执行完毕
3)finally 清理线程:这里有行比较重要的代码 “monitor.threadFinished(this);” ,这个monitor是什么呢? 往下看。(Q1)
中间循环运行比较复杂的是process_sampler(sam, null, threadContext); 这个方法会真正触发客户端的测试代码的地方,代码很长就略去了,核心的逻辑大概如下:
1)分析Sampler是否是TransactionSampler, 若是解析Transaction 范围的一组Sampler Pack 进行递归process
2)Sampler.sample(Entry e)方法,产生一个SampleResult
3)把result包装成一个SampleEvent 并通知所有的监听器
所有的 SampleListener #sampleOccur 方法被触发, ResultCollector 就会有相应的措施来保存测试结果。
附接口 Sampler(主要有JavaSampler / TransationSampler / BeanShellSampler 等), SampleListener (最终要的是ResultCollector,另外还有ResultAction,Summariser等)代码:
public interface Sampler extends Serializable, TestElement { /** * Obtains statistics about the given Entry, and packages the information * into a SampleResult. */ SampleResult sample(Entry e); } public interface SampleListener { /** * A sample has started and stopped. */ void sampleOccurred(SampleEvent e); /** * A sample has started. */ void sampleStarted(SampleEvent e); /** * A sample has stopped. */ void sampleStopped(SampleEvent e); }
留下问题Q1: “monitor.threadFinished(this);” ,这个monitor是什么呢?
这个monitor其实就当前Thread 所在的 ThreadGroup,这里相当与对ThreadGroup的一个回调,如果有些资源清理必须在同一个线程中做的话就会很有用,比如一个case,我的测试代码中需要一个JNDI Context 进行lookup,那么这个JNDI Context 的close工作应该是在创建他的 同一个线程中去做,那么线程结束的时候去清理是最好不过了,所以可以重写ThreadGroup的threadFinished(JMeterThread)方法:
@Override public void threadFinished(JMeterThread thread) { super.threadFinished(thread); Context ctx = (Context) (thread instanceof ITestResourceHolder ? ((ITestResourceHolder) thread).getResourceMap().get( JMeterTestResource.JNDI_CONTEXT) : null); if (ctx != null) { try { log.debug("Thread " + Thread.currentThread().getName() + " closing InitialContext " + ctx); ctx.close(); } catch (NamingException e) { log.error("Exception occurred when try to close the InitialContext ", e); } finally { ((ITestResourceHolder) thread).getResourceMap().clear(); } } }
和JMeterEngine一样,我在扩展JMeterThread时顺便实现了ITestResourceHolder接口用来维护额外的线程变量(比如JNDIContext).
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