优化ThreadPoolNotifyAlarmHandler下的空指针异常

[zhuanghaozhe]

程序会监控线程池中每个任务的执行时间，如果执行时间超过了executeTimeOut，就会异步发送任务超时警告，执行ThreadPoolNotifyAlarmHandler类的asyncSendExecuteTimeOutAlarm方法。但如果此线程池在创建的时候，在DynamicThreadPoolPostProcessor类的postProcessAfterInitialization方法中向服务端请求该线程池的配置参数时发生错误。就会导致此线程池对应的threadPoolNotifyAlarm未被放入GlobalNotifyAlarmManage的NOTIFY_ALARM_MAP当中，进而导致在异步发送任务超时警告ThreadPoolNotifyAlarmHandler类的asyncSendExecuteTimeOutAlarm方法时，发生空指针异常

相关代码：

ThreadPoolNotifyAlarm threadPoolNotifyAlarm = GlobalNotifyAlarmManage.get(threadPoolId);// null
if (!threadPoolNotifyAlarm.getIsAlarm()) {
    return;
}

异常如下：

Exception in thread "message-consume-3" java.lang.NullPointerException
	at cn.hippo4j.core.executor.ThreadPoolNotifyAlarmHandler.asyncSendExecuteTimeOutAlarm(ThreadPoolNotifyAlarmHandler.java:171)
	at cn.hippo4j.core.executor.DynamicThreadPoolExecutor.afterExecute(DynamicThreadPoolExecutor.java:100)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1157)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)