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Improve graceful shutdown #1820

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May 31, 2018
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Original file line number Diff line number Diff line change
Expand Up @@ -16,66 +16,65 @@
*/
package org.apache.dubbo.bootstrap;

import com.alibaba.dubbo.common.extension.ExtensionLoader;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.config.DubboShutdownHook;
import com.alibaba.dubbo.config.ServiceConfig;
import com.alibaba.dubbo.registry.support.AbstractRegistryFactory;
import com.alibaba.dubbo.rpc.Protocol;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;

/**
* A bootstrap class to easily start and stop Dubbo via programmatic API.
* The bootstrap class will be responsible to cleanup the resources during stop.
*/
public class DubboBootstrap {

private static final Logger logger = LoggerFactory.getLogger(DubboBootstrap.class);

/**
* The list of ServiceConfig
*/
private List<ServiceConfig> serviceConfigList;

/**
* Has it already been destroyed or not?
* Whether register the shutdown hook during start?
*/
private final AtomicBoolean destroyed;
private final boolean registerShutdownHookOnStart;

/**
* The shutdown hook used when Dubbo is running under embedded environment
*/
private Thread shutdownHook;
private DubboShutdownHook shutdownHook;

public DubboBootstrap() {
this(true, DubboShutdownHook.getDubboShutdownHook());
}

public DubboBootstrap(boolean registerShutdownHookOnStart) {
this(registerShutdownHookOnStart, DubboShutdownHook.getDubboShutdownHook());
}

public DubboBootstrap(boolean registerShutdownHookOnStart, DubboShutdownHook shutdownHook) {
this.serviceConfigList = new ArrayList<ServiceConfig>();
this.destroyed = new AtomicBoolean(false);
this.shutdownHook = new Thread(new Runnable() {
@Override
public void run() {
if (logger.isInfoEnabled()) {
logger.info("Run shutdown hook now.");
}
destroy();
}
}, "DubboShutdownHook");
this.shutdownHook = shutdownHook;
this.registerShutdownHookOnStart = registerShutdownHookOnStart;
}

/**
* Register service config to bootstrap, which will be called during {@link DubboBootstrap#stop()}
* @param serviceConfig the service
* @return the bootstrap instance
*/
public DubboBootstrap regsiterServiceConfig(ServiceConfig serviceConfig) {
public DubboBootstrap registerServiceConfig(ServiceConfig serviceConfig) {
serviceConfigList.add(serviceConfig);
return this;
}

public void start() {
registerShutdownHook();
if (registerShutdownHookOnStart) {
registerShutdownHook();
} else {
// DubboShutdown hook has been registered in AbstractConfig,
// we need to remove it explicitly
removeShutdownHook();
}
for (ServiceConfig serviceConfig: serviceConfigList) {
serviceConfig.export();
}
Expand All @@ -85,8 +84,10 @@ public void stop() {
for (ServiceConfig serviceConfig: serviceConfigList) {
serviceConfig.unexport();
}
destroy();
removeShutdownHook();
shutdownHook.destroyAll();
if (registerShutdownHookOnStart) {
removeShutdownHook();
}
}

/**
Expand All @@ -107,27 +108,4 @@ public void removeShutdownHook() {
// ignore - VM is already shutting down
}
}

/**
* Destroy all the resources, including registries and protocols.
*/
private void destroy() {
if (!destroyed.compareAndSet(false, true)) {
return;
}
// destroy all the registries
AbstractRegistryFactory.destroyAll();
// destroy all the protocols
ExtensionLoader<Protocol> loader = ExtensionLoader.getExtensionLoader(Protocol.class);
for (String protocolName : loader.getLoadedExtensions()) {
try {
Protocol protocol = loader.getLoadedExtension(protocolName);
if (protocol != null) {
protocol.destroy();
}
} catch (Throwable t) {
logger.warn(t.getMessage(), t);
}
}
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,9 @@ public abstract class AbstractConfig implements Serializable {
legacyProperties.put("dubbo.consumer.retries", "dubbo.service.max.retry.providers");
legacyProperties.put("dubbo.consumer.check", "dubbo.service.allow.no.provider");
legacyProperties.put("dubbo.service.url", "dubbo.service.address");

// this is only for compatibility
Runtime.getRuntime().addShutdownHook(DubboShutdownHook.getDubboShutdownHook());
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This will lead to the coexistence of spring hooks,If the spring hook destroys the context before dubbo, the user code uses the aop feature, or calls the getBean method, dubbo gracefully shutdown and reports that the bean was not found.
Only dubbo hooks are registered in non-spring containers.

}

protected String id;
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Original file line number Diff line number Diff line change
@@ -0,0 +1,85 @@
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.alibaba.dubbo.config;

import com.alibaba.dubbo.common.extension.ExtensionLoader;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.registry.support.AbstractRegistryFactory;
import com.alibaba.dubbo.rpc.Protocol;

import java.util.concurrent.atomic.AtomicBoolean;

/**
* The shutdown hook thread to do the clean up stuff.
* This is a singleton in order to ensure there is only one shutdown hook registered.
* Because {@link ApplicationShutdownHooks} use {@link java.util.IdentityHashMap}
* to store the shutdown hooks.
*/
public class DubboShutdownHook extends Thread {

private static final Logger logger = LoggerFactory.getLogger(DubboShutdownHook.class);

private static final DubboShutdownHook dubboShutdownHook = new DubboShutdownHook("DubboShutdownHook");

public static DubboShutdownHook getDubboShutdownHook() {
return dubboShutdownHook;
}

/**
* Has it already been destroyed or not?
*/
private final AtomicBoolean destroyed;

private DubboShutdownHook(String name) {
super(name);
this.destroyed = new AtomicBoolean(false);
}

@Override
public void run() {
if (logger.isInfoEnabled()) {
logger.info("Run shutdown hook now.");
}
destroyAll();
}

/**
* Destroy all the resources, including registries and protocols.
*/
public void destroyAll() {
if (!destroyed.compareAndSet(false, true)) {
return;
}
// destroy all the registries
AbstractRegistryFactory.destroyAll();
// destroy all the protocols
ExtensionLoader<Protocol> loader = ExtensionLoader.getExtensionLoader(Protocol.class);
for (String protocolName : loader.getLoadedExtensions()) {
try {
Protocol protocol = loader.getLoadedExtension(protocolName);
if (protocol != null) {
protocol.destroy();
}
} catch (Throwable t) {
logger.warn(t.getMessage(), t);
}
}
}


}
Original file line number Diff line number Diff line change
Expand Up @@ -460,4 +460,12 @@ public void destory() {
}
}

/**
* Just for compatibility.
* It should be deleted in the next major version, say 2.7.x.
*/
@Deprecated
public static void destroyAll() {
DubboShutdownHook.getDubboShutdownHook().destroyAll();
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,11 @@ public class DubboApplicationListener implements ApplicationListener<Application
private DubboBootstrap dubboBootstrap;

public DubboApplicationListener() {
dubboBootstrap = new DubboBootstrap();
dubboBootstrap = new DubboBootstrap(false);
}

public DubboApplicationListener(DubboBootstrap dubboBootstrap) {
this.dubboBootstrap = dubboBootstrap;
}

@Override
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Original file line number Diff line number Diff line change
@@ -0,0 +1,59 @@
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.alibaba.dubbo.config.spring.initializer;

import com.alibaba.dubbo.config.DubboShutdownHook;
import org.apache.dubbo.bootstrap.DubboBootstrap;
import org.junit.Test;
import org.mockito.Mockito;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class DubboApplicationListenerTest {

@Test
public void testTwoShutdownHook() {
DubboShutdownHook spyHook = Mockito.spy(DubboShutdownHook.getDubboShutdownHook());
ClassPathXmlApplicationContext applicationContext = getApplicationContext(spyHook, true);
applicationContext.refresh();
applicationContext.close();
// shutdown hook can't be verified, because it will executed after main thread has finished.
// so we can only verify it by manually run it.
try {
spyHook.start();
spyHook.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
Mockito.verify(spyHook, Mockito.times(2)).destroyAll();
}

@Test
public void testOneShutdownHook() {
DubboShutdownHook spyHook = Mockito.spy(DubboShutdownHook.getDubboShutdownHook());
ClassPathXmlApplicationContext applicationContext = getApplicationContext(spyHook, false);
applicationContext.refresh();
applicationContext.close();
Mockito.verify(spyHook, Mockito.times(1)).destroyAll();
}

private ClassPathXmlApplicationContext getApplicationContext(DubboShutdownHook hook, boolean registerHook) {
DubboBootstrap bootstrap = new DubboBootstrap(registerHook, hook);
ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext();
applicationContext.addApplicationListener(new DubboApplicationListener(bootstrap));
return applicationContext;
}
}
5 changes: 5 additions & 0 deletions dubbo-container/dubbo-container-spring/pom.xml
Original file line number Diff line number Diff line change
Expand Up @@ -39,5 +39,10 @@
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo-config-spring</artifactId>
<version>${project.parent.version}</version>
</dependency>
</dependencies>
</project>
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.common.utils.ConfigUtils;
import com.alibaba.dubbo.config.spring.initializer.DubboApplicationListener;
import com.alibaba.dubbo.container.Container;

import org.springframework.context.support.ClassPathXmlApplicationContext;
Expand All @@ -44,6 +45,7 @@ public void start() {
configPath = DEFAULT_SPRING_CONFIG;
}
context = new ClassPathXmlApplicationContext(configPath.split("[,\\s]+"));
context.addApplicationListener(new DubboApplicationListener());
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If you are interested in ContextRefreshedEvent or other start events, you will not receive a notification. Unless specified not to refresh, eg:

context = new ClassPathXmlApplicationContext(configPath.split("[,\\s]+"), false);
context.addApplicationListener(new DubboApplicationListener());
context.refresh();

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@ralf0131
spring-boot defaults to registration hooks. Spring does not register by default.
Registering hooks by default is a good idea.
eg:

 if(context instanceof AbstractApplicationContext) {
     AbstractApplicationContext ctx = (AbstractApplicationContext)context;
     ctx.registerShutdownHook();
}

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Yes, we should call refresh(). I will fix it.

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Yes, we should also call registerShutdownHook() to ensure there is at least one shutdown hook registered, because the current implementation assumes that when Dubbo detects it is running under spring, it will automatically remove the previously registered shutdownhook.
Thanks for the reminder.

context.start();
}

Expand Down