JUC学习-23-线程池拒绝策略

JUC学习-23-线程池拒绝策略

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四种拒绝策略

1、默认：AbortPolicy 直接抛异常

public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
throw new RejectedExecutionException("Task " + r.toString() +
" rejected from " +
e.toString());
}
}

2、CallerRunsPolicy 如果线程池没有关闭 执行run方法

public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
if (!e.isShutdown()) {
r.run();
}
}
}

3、DiscardOldestPolicy 如果线程池没有关闭，会将队列最强面的任务弹出(淘汰),并将新的任务放入到对流末尾

public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
if (!e.isShutdown()) {
e.getQueue().poll();
e.execute(r);
}
}

4、DiscardPolicy 什么也不做

public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
}