項目在重新發布的過程中，如果有的請求時間比較長，還沒執行完成，此時重啟的話就會導致請求中斷，影響業務功能，優雅重啟可以保證在停止的時候，不接收外部的新的請求，等待未完成的請求執行完成，這樣可以保證數據的完整性。
Spring Boot 1.X
import java.util.concurrent.Executor; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; import org.apache.catalina.connector.Connector; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.boot.context.embedded.ConfigurableEmbeddedServletContainer; import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizer; import org.springframework.boot.context.embedded.tomcat.TomcatConnectorCustomizer; import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory; import org.springframework.context.ApplicationListener; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.event.ContextClosedEvent; /** * Spring Boot1.X Tomcat容器優雅停機 * @author yinjihuan * */ @Configuration public class ShutdownConfig { /** * 用於接受shutdown事件 * @return */ @Bean public GracefulShutdown gracefulShutdown() { return new GracefulShutdown(); } /** * 用於注入 connector * @return */ @Bean public EmbeddedServletContainerCustomizer tomcatCustomizer() { return new EmbeddedServletContainerCustomizer() { @Override public void customize(ConfigurableEmbeddedServletContainer container) { if (container instanceof TomcatEmbeddedServletContainerFactory) { ((TomcatEmbeddedServletContainerFactory) container).addConnectorCustomizers(gracefulShutdown()); } } }; } private static class GracefulShutdown implements TomcatConnectorCustomizer, ApplicationListener { private static final Logger log = LoggerFactory.getLogger(GracefulShutdown.class); private volatile Connector connector; private final int waitTime = 120; @Override public void customize(Connector connector) { this.connector = connector; } @Override public void onApplicationEvent(ContextClosedEvent event) { this.connector.pause(); Executor executor = this.connector.getProtocolHandler().getExecutor(); if (executor instanceof ThreadPoolExecutor) { try { ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executor; log.info("shutdown start"); threadPoolExecutor.shutdown(); log.info("shutdown end"); if (!threadPoolExecutor.awaitTermination(waitTime, TimeUnit.SECONDS)) { log.info("Tomcat 進程在" + waitTime + "秒內無法結束，嘗試強制結束"); } log.info("shutdown success"); } catch (InterruptedException ex) { Thread.currentThread().interrupt(); } } } }} Spring Boot 2.X
import java.util.concurrent.Executor; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; import org.apache.catalina.connector.Connector; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.boot.web.embedded.tomcat.TomcatConnectorCustomizer; import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory; import org.springframework.boot.web.servlet.server.ServletWebServerFactory; import org.springframework.context.ApplicationListener; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.event.ContextClosedEvent; /** * Spring Boot2.X Tomcat容器優雅停機 * @author yinjihuan * */@Configurationpublic class ShutdownConfig { /** * 用於接受shutdown事件 * @return */ @Bean public GracefulShutdown gracefulShutdown() { return new GracefulShutdown(); } @Bean public ServletWebServerFactory servletContainer() { TomcatServletWebServerFactory tomcat = new TomcatServletWebServerFactory(); tomcat.addConnectorCustomizers(gracefulShutdown()); return tomcat; } private static class GracefulShutdown implements TomcatConnectorCustomizer, ApplicationListener { private static final Logger log = LoggerFactory.getLogger(GracefulShutdown.class); private volatile Connector connector; private final int waitTime = 120; @Override public void customize(Connector connector) { this.connector = connector; } @Override public void onApplicationEvent(ContextClosedEvent event) { this.connector.pause(); Executor executor = this.connector.getProtocolHandler().getExecutor(); if (executor instanceof ThreadPoolExecutor) { try { ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executor; log.info("shutdown start"); threadPoolExecutor.shutdown(); log.info("shutdown end"); if (!threadPoolExecutor.awaitTermination(waitTime, TimeUnit.SECONDS)) { log.info("Tomcat 進程在" + waitTime + "秒內無法結束，嘗試強制結束"); } log.info("shutdown success"); } catch (InterruptedException ex) { Thread.currentThread().interrupt(); } } } }} 重啟服務腳本：
NG="zh_CN.UTF-8"pid=`ps ax | grep fangjia-youfang-web | grep java | head -1 | awk '{print $1}'`echo $pid#kill $pidcurl -X POST http://127.0.0.1:8086/shutdown?token=認證信息while [[ $pid != "" ]]; do echo '服務停止中...' sleep 1 pid=`ps ax | grep fangjia-youfang-web | grep java | head -1 | awk '{print $1}'`doneecho '服務停止成功,開始重啟服務...'java -jar xxx.jar在重啟之前首先發送重啟命令到endpoint，或者用kill 進程ID的方式，千萬不要用kill -9。
然後循環檢測進程是否存在，如果服務正常停止了，進程也就不存在了，如果進程還在，證明還有未處理完的請求，停止1秒，繼續檢測。
關於重啟服務，建議用kill方式，這樣就不用依賴spring-boot-starter-actuator，如果用endpoint方式，則需要控制好權限，不然隨時都有可能被人重啟了，可以用security來控制權限，我這邊是自己用過濾器來控制的。
如果用actuator方式重啟的話需要配置啟用重啟功能:
1.x配置如下：
endpoints.shutdown.enabled=true
2.x配置就比較多了，默認只暴露了幾個常用的，而且訪問地址也有變化，比如health, 以前是直接訪問/health,現在需要 /actuator/health才能訪問。我們可以通過配置來兼容之前的訪問地址。
shutdown默認是不暴露的，可以通過配置暴露並開始，配置如下：
#訪問路徑，配置後就和1.x版本路徑一樣 management.endpoints.web.base-path=/ # 暴露所有，也可以暴露單個或多個management.endpoints.web.exposure.include=*# 開啟shutdownmanagement.endpoint.shutdown.enabled=true
#訪問路徑，配置後就和1.x版本路徑一樣
management.endpoints.web.base-path=/
# 暴露所有，也可以暴露單個或多個
management.endpoints.web.exposure.include=*
# 開啟shutdown
management.endpoint.shutdown.enabled=true
文檔請參考：https://docs.spring.io/spring-boot/docs/2.0.2.RELEASE/reference/htmlsingle/#production-ready
如何測試
測試的話我們可以寫一個簡單的接口，在接口中等待，然後執行腳本停止項目，如果正常的話會輸出服務停止中，等到你的接口執行完成，進程才會消失掉，但是如果超過了你配置的等待時間就會強行退出。
@GetMapping("/hello")public String hello() { System.out.println("req........."); try { Thread.sleep(1000 * 60 * 3); } catch (InterruptedException e) { e.printStackTrace(); } return "hello"; }需要注意的問題
如果你的項目中有用到其他的線程池，比如Spring的ThreadPoolTaskExecutor，不熟悉的同學可以參考我的這篇文章《Spring Boot Async異步執行》
在發送停止命令後如果ThreadPoolTaskExecutor有線程還沒處理完的話，這個時候進程是不會自動關閉的。這個時候我們需要對線程池進行關閉處理，增加代碼如下：
AsyncTaskExecutePool asyncTaskExecutePool = event.getApplicationContext().getBean(AsyncTaskExecutePool.class);Executor executors = asyncTaskExecutePool.getAsyncExecutor();try { if (executors instanceof ThreadPoolTaskExecutor) { ThreadPoolTaskExecutor threadPoolExecutor = (ThreadPoolTaskExecutor) executors; log.info("Async shutdown start"); threadPoolExecutor.setWaitForTasksToCompleteOnShutdown(true); threadPoolExecutor.setAwaitTerminationSeconds(waitTime); threadPoolExecutor.shutdown(); } } catch (Exception ex) { Thread.currentThread().interrupt(); }ThreadPoolTaskExecutor只有shutdown方法，沒有awaitTermination方法，通過查看源碼，在shutdown之前設置setWaitForTasksToCompleteOnShutdown和setAwaitTerminationSeconds同樣能實現awaitTermination。
源碼如下：
public void shutdown() { if (logger.isInfoEnabled()) { logger.info("Shutting down ExecutorService" + (this.beanName != null ? " '" + this.beanName + "'" : "")); } if (this.executor != null) { if (this.waitForTasksToCompleteOnShutdown) { this.executor.shutdown(); } else { for (Runnable remainingTask : this.executor.shutdownNow()) { cancelRemainingTask(remainingTask); } } awaitTerminationIfNecessary(this.executor); }}當waitForTasksToCompleteOnShutdown為true的時候就直接調用executor.shutdown();，最後執行awaitTerminationIfNecessary方法。
private void awaitTerminationIfNecessary(ExecutorService executor) { if (this.awaitTerminationSeconds > 0) { try { if (!executor.awaitTermination(this.awaitTerminationSeconds, TimeUnit.SECONDS)) { if (logger.isWarnEnabled()) { logger.warn("Timed out while waiting for executor" + (this.beanName != null ? " '" + this.beanName + "'" : "") + " to terminate"); } } } catch (InterruptedException ex) { if (logger.isWarnEnabled()) { logger.warn("Interrupted while waiting for executor" + (this.beanName != null ? " '" + this.beanName + "'" : "") + " to terminate"); } Thread.currentThread().interrupt(); } } }awaitTerminationIfNecessary中會判斷屬性awaitTerminationSeconds 如果與值的話就執行關閉等待檢測邏輯，跟我們處理tomcat關閉的代碼是一樣的。
發現這樣做之後好像沒什麼效果，於是我換了一種寫法，直接通過獲取ThreadPoolTaskExecutor中的ThreadPoolExecutor來執行關閉邏輯：
AsyncTaskExecutePool asyncTaskExecutePool = event.getApplicationContext().getBean(AsyncTaskExecutePool.class);Executor executors = asyncTaskExecutePool.getAsyncExecutor();try { if (executors instanceof ThreadPoolTaskExecutor) { ThreadPoolTaskExecutor threadPoolExecutor = (ThreadPoolTaskExecutor) executors; log.info("Async shutdown start"); threadPoolExecutor.getThreadPoolExecutor().shutdown(); log.info("Async shutdown end"+threadPoolExecutor.getThreadPoolExecutor().isTerminated()); if (!threadPoolExecutor.getThreadPoolExecutor().awaitTermination(waitTime, TimeUnit.SECONDS)) { log.info("Tomcat 進程在" + waitTime + "秒內無法結束，嘗試強制結束"); } log.info("Async shutdown success"); } } catch (Exception ex) { Thread.currentThread().interrupt(); }這是方式也沒用達到我想要的效果，當我發出kill命令之後，直接就退出了，其實我有一個後臺線程在ThreadPoolTaskExecutor中運行，通過輸出的日誌看到，只要調用了shutdown，isTerminated方法返回的就是true,說已經關閉了，這塊還沒找到原因，有研究出來的小夥伴還請分享出來。
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