純潔的微笑
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<ContextClosedEvent> {
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
*
*/
@Configuration
public 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<ContextClosedEvent> {
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 $pid
curl -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}'`
done
echo '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。
然后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，配置后就和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，然后執行腳本停止項目，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》
在發送停止命令后如果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();，最后執行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。
發現這樣做之后好像沒什么效果，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命令之后，直接就退出了，其實我有一個后台線程在ThreadPoolTaskExecutor中運行，通過輸出的日志看到，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，有研究出來的小伙伴還請分享出來。
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