记一次源码探索-线程池提交一个任务到底有多少个线程在运行 java

这次主要有一个这样的疑惑

final void runWorker(Worker w) { Thread wt = Thread.currentThread(); Runnable task = w.firstTask; w.firstTask = null; w.unlock(); // allow interrupts boolean completedAbruptly = true; try { while (task != null || (task = getTask()) != null) { w.lock(); // If pool is stopping, ensure thread is interrupted; // if not, ensure thread is not interrupted.This // requires a recheck in second case to deal with // shutdownNow race while clearing interrupt if ((runStateAtLeast(ctl.get(), STOP) || (Thread.interrupted() && runStateAtLeast(ctl.get(), STOP))) && !wt.isInterrupted()) wt.interrupt(); try { beforeExecute(wt, task); Throwable thrown = null; try { task.run(); } catch (RuntimeException x) { thrown = x; throw x; } catch (Error x) { thrown = x; throw x; } catch (Throwable x) { thrown = x; throw new Error(x); } finally { afterExecute(task, thrown); } } finally { task = null; w.completedTasks++; w.unlock(); } } completedAbruptly = false; } finally { processWorkerExit(w, completedAbruptly); } }

这里的话，task又run了一下，猜测是不是线程池提交一个任务后任务本身又起了一个线程，于是用一下代码验证一下

public class ThreadPool { private static ExecutorService pool; public static void main( String[] args ) { //maximumPoolSize设置为2 ，拒绝策略为AbortPolic策略，直接抛出异常 pool = new ThreadPoolExecutor(2, 10, 1000, TimeUnit.MILLISECONDS, new SynchronousQueue(), Executors.defaultThreadFactory(),new ThreadPoolExecutor.AbortPolicy()); for(int i=0; i<3; i++) { pool.execute(new ThreadTask()); } }public static class ThreadTask implements Runnable{public ThreadTask() {}public void run() { System.out.println(Thread.currentThread().getName()); } } }

【记一次源码探索-线程池提交一个任务到底有多少个线程在运行】于是发现下图所示