Spring Boot 1.X 和 2.X 优雅重启实战
项目在重新发布的过程中，如果有的请求时间比较长，还没执行完成，此时重启的话就会导致请求中断，影响业务功能，优雅重启可以保证在停止的时候，不接收外部的新的请求，等待未完成的请求执行完成，这样可以保证数据的完整性。
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容器优雅停机
* @author yinjihuan
*
*/
@Configuration
public class ShutdownConfig {
/**
* 用于接受shutdown事件
* @return
*/
@Bean
public GracefulShutdown gracefulShutdown() {
return new GracefulShutdown();
}
/**
* 用于注入 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 进程在" + waitTime + "秒内无法结束，尝试强制结束");
}
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容器优雅停机
* @author yinjihuan
*
*/
@Configuration
public class ShutdownConfig {
/**
* 用于接受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 进程在" + waitTime + "秒内无法结束，尝试强制结束");
}
log.info("shutdown success");
} catch (InterruptedException ex) {
Thread.currentThread().interrupt();
}
}
}
}
}
重启服务脚本：
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=认证信息
while [[ $pid != "" ]]; do
echo '服务停止中...'
sleep 1
pid=`ps ax | grep fangjia-youfang-web | grep java | head -1 | awk '{print $1}'`
done
echo '服务停止成功,开始重启服务...'
java -jar xxx.jar
在重启之前首先发送重启命令到endpoint，或者用kill 进程ID的方式，千万不要用kill -9。
然后循环检测进程是否存在，如果服务正常停止了，进程也就不存在了，如果进程还在，证明还有未处理完的请求，停止1秒，继续检测。
关于重启服务，建议用kill方式，这样就不用依赖spring-boot-starter-actuator，如果用endpoint方式，则需要控制好权限，不然随时都有可能被人重启了，可以用security来控制权限，我这边是自己用过滤器来控制的。
如果用actuator方式重启的话需要配置启用重启功能:
1.x配置如下：
endpoints.shutdown.enabled=true
2.x配置就比较多了，默认只暴露了几个常用的，而且访问地址也有变化，比如health, 以前是直接访问/health,现在需要 /actuator/health才能访问。我们可以通过配置来兼容之前的访问地址。
shutdown默认是不暴露的，可以通过配置暴露并开始，配置如下：
#访问路径，配置后就和1.x版本路径一样
management.endpoints.web.base-path=/
# 暴露所有，也可以暴露单个或多个
management.endpoints.web.exposure.include=*
# 开启shutdown
management.endpoint.shutdown.enabled=true
文档请参考：https://docs.spring.io/spring-boot/docs/2.0.2.RELEASE/reference/htmlsingle/#production-ready
如何测试
测试的话我们可以写一个简单的接口，在接口中等待，然后执行脚本停止项目，如果正常的话会输出服务停止中，等到你的接口执行完成，进程才会消失掉，但是如果超过了你配置的等待时间就会强行退出。
@GetMapping("/hello")
public String hello() {
System.out.println("req.........");
try {
Thread.sleep(1000 * 60 * 3);
} catch (InterruptedException e) {
e.printStackTrace();
}
return "hello";
}
需要注意的问题
如果你的项目中有用到其他的线程池，比如Spring的ThreadPoolTaskExecutor，不熟悉的同学可以参考我的这篇文章《Spring Boot Async异步执行》
在发送停止命令后如果ThreadPoolTaskExecutor有线程还没处理完的话，这个时候进程是不会自动关闭的。这个时候我们需要对线程池进行关闭处理，增加代码如下：
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，没有awaitTermination方法，通过查看源码，在shutdown之前设置setWaitForTasksToCompleteOnShutdown和setAwaitTerminationSeconds同样能实现awaitTermination。
源码如下：
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);
}
}
当waitForTasksToCompleteOnShutdown为true的时候就直接调用executor.shutdown();，最后执行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中会判断属性awaitTerminationSeconds 如果与值的话就执行关闭等待检测逻辑，跟我们处理tomcat关闭的代码是一样的。
发现这样做之后好像没什么效果，于是我换了一种写法，直接通过获取ThreadPoolTaskExecutor中的ThreadPoolExecutor来执行关闭逻辑：
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 进程在" + waitTime + "秒内无法结束，尝试强制结束");
}
log.info("Async shutdown success");
}
} catch (Exception ex) {
Thread.currentThread().interrupt();
}
这是方式也没用达到我想要的效果，当我发出kill命令之后，直接就退出了，其实我有一个后台线程在ThreadPoolTaskExecutor中运行，通过输出的日志看到，只要调用了shutdown，isTerminated方法返回的就是true,说已经关闭了，这块还没找到原因，有研究出来的小伙伴还请分享出来。
推荐相关阅读：
《Spring Boot 使用WebAsyncTask异步返回结果》
《Spring Boot Async异步执行任务》
《面试题-实现多线程的方式》
更多技术分享请加我微信，我拉你进群进行交流：
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666
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文章和留言都翻到11页了 没有OOM
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朋友，翻页到11页，及以后，会出现OOM，无法访问
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版本号是多少，你可以下载哪个代码仓库，jdk选1.8 直接跑就行
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