最近在生产环境和预发环境经常出现java.lang.IllegalStateException: urls to invokers error .invokerUrls.size :1, invoker.size :0，这一类的error错误，具体错误信息如下
java.lang.IllegalStateException: urls to invokers error .invokerUrls.size :1, invoker.size :0. urls :[dubbo://192.168.137.13:20881/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=dubbodemoprovider&dubbo=2.5.3.6&interface=com.alibaba.dubbo.demo.DemoService&methods=complexInvoke,complex,Timeout,complexObject,complexUser,sayHello2,$$sayHelloTest,complexArray2,hessianTest,sayHello,HelloWorld,hessianMapTest,complexArray,hessianSerialable,ThrowException,mockDate&pid=3094&revision=2.5.3.8-SNAPSHOT&side=provider×tamp=1493780202580] at com.alibaba.dubbo.registry.integration.RegistryDirectory.refreshInvoker(RegistryDirectory.java:229) [dubbo-2.5.3.9.jar:2.5.3.9] at com.alibaba.dubbo.registry.integration.RegistryDirectory.notify(RegistryDirectory.java:195) [dubbo-2.5.3.9.jar:2.5.3.9] at com.alibaba.dubbo.registry.support.AbstractRegistry.notify(AbstractRegistry.java:449) [dubbo-2.5.3.9.jar:2.5.3.9] at com.alibaba.dubbo.registry.support.FailbackRegistry.doNotify(FailbackRegistry.java:273) [dubbo-2.5.3.9.jar:2.5.3.9] at com.alibaba.dubbo.registry.support.FailbackRegistry.notify(FailbackRegistry.java:259) [dubbo-2.5.3.9.jar:2.5.3.9]
at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry.access$400(ZookeeperRegistry.java:45) [dubbo-2.5.3.9.jar:2.5.3.9] at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry$3.childChanged(ZookeeperRegistry.java:163) [dubbo-2.5.3.9.jar:2.5.3.9] at com.alibaba.dubbo.remoting.zookeeper.zkclient.ZkclientZookeeperClient$2.handleChildChange(ZkclientZookeeperClient.java:82) [dubbo-2.5.3.9.jar:2.5.3.9] at org.I0Itec.zkclient.ZkClient$7.run(ZkClient.java:568) [zkclient-0.1.jar:na] at org.I0Itec.zkclient.ZkEventThread.run(ZkEventThread.java:71) [zkclient-0.1.jar:na]
首先出现该类型错误，并不影响正常调用，dubbo中有保护机制，当所有的的provider都被disable后，会保留最后一个被disable的provider，提供正常的服务。具体的实现代码如下RegistryDirectory类中的如下方法
代码语言：javascript复制private void refreshInvoker(List<URL> invokerUrls){
if (invokerUrls != null && invokerUrls.size() == 1 && invokerUrls.get(0) != null
&& Constants.EMPTY_PROTOCOL.equals(invokerUrls.get(0).getProtocol())) {
this.forbidden = true; // 禁止访问
this.methodInvokerMap = null; // 置空列表
destroyAllInvokers(); // 关闭所有Invoker
} else {
this.forbidden = false; // 允许访问
Map<String, Invoker<T>> oldUrlInvokerMap = this.urlInvokerMap; // local reference
if (invokerUrls.size() == 0 && this.cachedInvokerUrls != null){
invokerUrls.addAll(this.cachedInvokerUrls);
} else {
this.cachedInvokerUrls = new HashSet<URL>();
this.cachedInvokerUrls.addAll(invokerUrls);//缓存invokerUrls列表，便于交叉对比
}
if (invokerUrls.size() ==0 ){
return;
}
Map<String, Invoker<T>> newUrlInvokerMap = toInvokers(invokerUrls) ;// 将URL列表转成Invoker列表
Map<String, List<Invoker<T>>> newMethodInvokerMap = toMethodInvokers(newUrlInvokerMap); // 换方法名映射Invoker列表
// state change
//如果计算错误，则不进行处理.
//这里是抛出具体错误的地方，当newUrlInvokerMap都为空时，这里会打印出ERROR日志
if (newUrlInvokerMap == null || newUrlInvokerMap.size() == 0 ){
logger.error(new IllegalStateException("urls to invokers error .invokerUrls.size :" invokerUrls.size() ", invoker.size :0. urls :" invokerUrls.toString()));
return ;
}
this.methodInvokerMap = multiGroup ? toMergeMethodInvokerMap(newMethodInvokerMap) : newMethodInvokerMap;
this.urlInvokerMap = newUrlInvokerMap;
try{
destroyUnusedInvokers(oldUrlInvokerMap,newUrlInvokerMap); // 关闭未使用的Invoker
}catch (Exception e) {
logger.warn("destroyUnusedInvokers error. ", e);
}
}
}具体是在进行灰度发布时，会先进行disable，会通过zookeeper通知到客户端，进行连接销毁，因为disable操作是单个进行，所以当操作到最后一个时，如果发现没有可用提供者，则会打印error日志，保留最后一个如下是AbstractRegistry类中的通知
代码语言：javascript复制protected void notify(URL url, NotifyListener listener, List<URL> urls) {
if (url == null) {
throw new IllegalArgumentException("notify url == null");
}
if (listener == null) {
throw new IllegalArgumentException("notify listener == null");
}
if ((urls == null || urls.size() == 0)
&& ! Constants.ANY_VALUE.equals(url.getServiceInterface())) {
logger.warn("Ignore empty notify urls for subscribe url " url);
return;
}
if (logger.isDebugEnabled()) {
logger.debug("Notify urls for subscribe url " url ", urls: " urls);
}
Map<String, List<URL>> result = new HashMap<String, List<URL>>();
for (URL u : urls) {
if (UrlUtils.isMatch(url, u)) {
String category = u.getParameter(Constants.CATEGORY_KEY, Constants.DEFAULT_CATEGORY);
List<URL> categoryList = result.get(category);
if (categoryList == null) {
categoryList = new ArrayList<URL>();
result.put(category, categoryList);
}
categoryList.add(u);
}
}
if (result.size() == 0) {
return;
}
Map<String, List<URL>> categoryNotified = notified.get(url);
if (categoryNotified == null) {
notified.putIfAbsent(url, new ConcurrentHashMap<String, List<URL>>());
categoryNotified = notified.get(url);
}
for (Map.Entry<String, List<URL>> entry : result.entrySet()) {
String category = entry.getKey();
List<URL> categoryList = entry.getValue();
categoryNotified.put(category, categoryList);
saveProperties(url);
listener.notify(categoryList);
}
}RegistryDirectory类中的通知
代码语言：javascript复制public synchronized void notify(List<URL> urls) {
List<URL> invokerUrls = new ArrayList<URL>();
List<URL> routerUrls = new ArrayList<URL>();
List<URL> configuratorUrls = new ArrayList<URL>();
for (URL url : urls) {
String protocol = url.getProtocol();
String category = url.getParameter(Constants.CATEGORY_KEY, Constants.DEFAULT_CATEGORY);
if (Constants.ROUTERS_CATEGORY.equals(category)
|| Constants.ROUTE_PROTOCOL.equals(protocol)) {
routerUrls.add(url);
} else if (Constants.CONFIGURATORS_CATEGORY.equals(category)
|| Constants.OVERRIDE_PROTOCOL.equals(protocol)) {
configuratorUrls.add(url);
} else if (Constants.PROVIDERS_CATEGORY.equals(category)) {
invokerUrls.add(url);
} else {
logger.warn("Unsupported category " category " in notified url: " url " from registry " getUrl().getAddress() " to consumer " NetUtils.getLocalHost());
}
}
// configurators
if (configuratorUrls != null && configuratorUrls.size() >0 ){
this.configurators = toConfigurators(configuratorUrls);
}
// routers
if (routerUrls != null && routerUrls.size() >0 ){
List<Router> routers = toRouters(routerUrls);
if(routers != null){ // null - do nothing
setRouters(routers);
}
}
List<Configurator> localConfigurators = this.configurators; // local reference
// 合并override参数
this.overrideDirectoryUrl = directoryUrl;
if (localConfigurators != null && localConfigurators.size() > 0) {
for (Configurator configurator : localConfigurators) {
this.overrideDirectoryUrl = configurator.configure(overrideDirectoryUrl);
}
}
// providers
refreshInvoker(invokerUrls);
}下面的连接销毁的方法是DubboInvoker中
代码语言：javascript复制//destroyUnusedInvokers这个方法中真正去销毁时会去调用该方法
public void destroy() {
//防止client被关闭多次.在connect per jvm的情况下，client.close方法会调用计数器-1，当计数器小于等于0的情况下，才真正关闭
if (super.isDestroyed()){
return ;
} else {
//dubbo check ,避免多次关闭
destroyLock.lock();
try{
if (super.isDestroyed()){
return ;
}
super.destroy();
if (invokers != null){
invokers.remove(this);
}
for (ExchangeClient client : clients) {
try {
client.close();
} catch (Throwable t) {
logger.warn(t.getMessage(), t);
}
}
}finally {
destroyLock.unlock();
}
}
}
