如何優(yōu)雅的關(guān)閉 Java線程池

簡介 在開發(fā)中使用線程池去執(zhí)行異步任務(wù)是比較普遍的操作
 ，然而雖然有些異步操作我們并不十分要求可靠性和實時性，但總歸業(yè)務(wù)還是需要的。如果在每次的服務(wù)發(fā)版過程中，我們不去介入線程池的停機邏輯，那么很有可能就會造成線程池中隊列的任務(wù)還未執(zhí)行完成，自然就會造成數(shù)據(jù)的丟失 。

探究

注意
，本文所有前提是對進程進行下線時使用的是kill -15

我們知道Spring已經(jīng)實現(xiàn)了自己的優(yōu)雅停機方案
，詳細請參考org.springframework.context.support.AbstractApplicationContext#registerShutdownHook，然后主要看調(diào)用的org.springframework.context.support.AbstractApplicationContext#doClose， 在這個方法里定義了容器銷毀的執(zhí)行順序

protected void doClose() {   // Check whether an actual close attempt is necessary...  if (this.active.get() && this.closed.compareAndSet(false, true)) {    if (logger.isDebugEnabled()) {     logger.debug("Closing " + this);   }   LiveBeansView.unregisterApplicationContext(this);   try {     // Publish shutdown event.    publishEvent(new ContextClosedEvent(this));   }   catch (Throwable ex) {     logger.warn("Exception thrown from ApplicationListener handling ContextClosedEvent", ex);   }   // Stop all Lifecycle beans, to avoid delays during inpidual destruction.   if (this.lifecycleProcessor != null) {     try {      this.lifecycleProcessor.onClose();    }    catch (Throwable ex) {      logger.warn("Exception thrown from LifecycleProcessor on context close", ex);    }   }   // Destroy all cached singletons in the context's BeanFactory.   destroyBeans();   // Close the state of this context itself.   closeBeanFactory();   // Let subclasses do some final clean-up if they wish...   onClose();   // Reset local application listeners to pre-refresh state.   if (this.earlyApplicationListeners != null) {     this.applicationListeners.clear();    this.applicationListeners.addAll(this.earlyApplicationListeners);   }   // Switch to inactive.   this.active.set(false);  } }

我們先主要關(guān)注下destroyBeans這個方法