Shutdown spring boot embedded jetty servlet container gracefully
1. 不优雅的原因
一般情况下，spring-boot服务停机时先关闭application context然后关闭jetty，两者关闭的时间差期间jetty依然再接收新的请求，而此时能够处理请求的相关资源已经在逐步关闭，导致抛出大量异常，直至jetty完全关闭。
2. 优雅的步骤
spring-boot收到服务停机请求时：
(1) jetty停止接收新的请求
(2) jetty处理收到停机请求之前的请求并返回
(3) 关闭application context
3. 具体实现
在application context关机事件发生时关闭jetty，server.stop()会实现以上(1)(2)两步的功能:1
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30@Slf4j
public class GracefulShutdownBean implements ApplicationListener<ContextClosedEvent> {
private static Server server;
@Override
public void onApplicationEvent(ContextClosedEvent event) {
if (server == null) {
log.error("Jetty server variable is null, this should not happen!");
return;
}
log.info("Entering shutdown for Jetty.");
if (!(server.getHandler() instanceof StatisticsHandler)) {
log.error("Root handler is not StatisticsHandler, graceful shutdown may not work at all!");
} else {
log.info("Active requests: " + ((StatisticsHandler) server.getHandler()).getRequestsActive());
}
try {
long begin = System.currentTimeMillis();
server.stop();
log.info("Shutdown took " + (System.currentTimeMillis() - begin) + " ms.");
} catch (Exception e) {
log.error("Fail to shutdown gracefully.", e);
}
}
public static void setServer(Server server) {
GracefulShutdownBean.server = server;
}
}
将GracefulShutdownBean声明为单例bean，交给spring管理:1
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public GracefulShutdownBean initGracefulShutdownBean() {
return new GracefulShutdownBean();
}
将jetty的server交给GracefulShutdownBean管理：1
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JettyServletWebServerFactory embeddedServletContainerFactory(("${server.port}") int port,
("${server.jetty.threadPool.maxThreads}") int maxThreads,
("${server.jetty.threadPool.minThreads}") int minThreads,
("${server.jetty.threadPool.idleTimeout}") int idleTimeout,
("${server.jetty.shutdown.waitTime}") int shutdownWaitTime) {
JettyServletWebServerFactory factory = new JettyServletWebServerFactory(port);
factory.addServerCustomizers(server -> {
QueuedThreadPool threadPool = server.getBean(QueuedThreadPool.class);
threadPool.setMaxThreads(maxThreads);
threadPool.setMinThreads(minThreads);
threadPool.setIdleTimeout(idleTimeout);
GracefulShutdownBean.setServer(server);
if (shutdownWaitTime > 0) {
StatisticsHandler handler = new StatisticsHandler();
handler.setHandler(server.getHandler());
server.setHandler(handler);
log.info("Shutdown wait time: " + shutdownWaitTime + "ms");
server.setStopTimeout(shutdownWaitTime);
// We will stop it through GracefulShutdownBean class.
server.setStopAtShutdown(false);
}
});
return factory;
}