线程池变更：executeTimeOut 变更极端情况下会出现异常

[lizhifuabc]

@OverRide
protected void beforeExecute(Thread t, Runnable r) {
// 案例1 ：executeTimeOut ：变更前 1，变更后 0
// 案例2 ：executeTimeOut ：变更前 0，变更后 1
if (executeTimeOut == null || executeTimeOut <= 0) {
return;
}
// 案例1 ：executeTimeOut ：变更前 1
// 案例2 ：executeTimeOut ：变更前 0，此时startTime空
this.startTime.set(SystemClock.now());
}
@OverRide
protected void afterExecute(Runnable r, Throwable t) {
// 案例1 ：executeTimeOut ：变更后 0，此时直接返回了，不会执行 this.startTime.remove();
// 案例2 ：executeTimeOut ：变更后 1， long startTime = this.startTime.get(); NPE
if (executeTimeOut == null || executeTimeOut <= 0) {
return;
}
try {
long startTime = this.startTime.get();
long endTime = SystemClock.now();
long executeTime;
boolean executeTimeAlarm = (executeTime = (endTime - startTime)) > executeTimeOut;
if (executeTimeAlarm && ApplicationContextHolder.getInstance() != null) {
ThreadPoolNotifyAlarmHandler notifyAlarmHandler = ApplicationContextHolder.getBean(ThreadPoolNotifyAlarmHandler.class);
if (notifyAlarmHandler != null) {
notifyAlarmHandler.asyncSendExecuteTimeOutAlarm(threadPoolId, executeTime, executeTimeOut, this);
}
}
} finally {
this.startTime.remove();
}
}

[magestacks]

@lizhifuabc 感谢反馈，如果有兴趣的话，可以提交个 pr。如无反馈，最近我会修复这个问题。