dubbo超时异常
dubbo超时异常
在调用dubbo服务时经常看到如下错误： Caused by: com.alibaba.dubbo.remoting.TimeoutException: Waiting server-side response timeout by scan timer.
源码分析
客户端调用远程服务时，本地会生成一个DefaultFuture，调用DefaultFuture.get()获取远程服务返回的结构,此方法获取锁，调用await方法，此时当前线程进入等待队列，此线程会有两种结果过：要么超时，抛出TimeOutException；如果被唤醒，则返回rpc的结果。 而这里的报错很明显是由于等待服务端返回结果时客户端超时异常，查看源码如下：
public class DefaultFuture implements ResponseFuture {
private static final Logger logger = LoggerFactory.getLogger(DefaultFuture.class);
private static final Map<Long, Channel> CHANNELS = new ConcurrentHashMap<Long, Channel>();
private static final Map<Long, DefaultFuture> FUTURES = new ConcurrentHashMap<Long, DefaultFuture>();
// invoke id.
private final long id;
private final Channel channel;
private final Request request;
private final int timeout;
private final Lock lock = new ReentrantLock();
private final Condition done = lock.newCondition();
private final long start = System.currentTimeMillis();
private volatile long sent;
private volatile Response response;
private volatile ResponseCallback callback;
public DefaultFuture(Channel channel, Request request, int timeout){
this.channel = channel;
this.request = request;
this.id = request.getId();
this.timeout = timeout > 0 ? timeout : channel.getUrl().getPositiveParameter(Constants.TIMEOUT_KEY, Constants.DEFAULT_TIMEOUT);
// put into waiting map.
FUTURES.put(id, this);
CHANNELS.put(id, channel);
}
public Object get() throws RemotingException {
return get(timeout);
}
public Object get(int timeout) throws RemotingException {
if (timeout <= 0) {
timeout = Constants.DEFAULT_TIMEOUT;
}
if (! isDone()) {
long start = System.currentTimeMillis();
lock.lock();
try {
while (! isDone()) {
done.await(timeout, TimeUnit.MILLISECONDS);
if (isDone() || System.currentTimeMillis() - start > timeout) {
break;
}
}
} catch (InterruptedException e) {
throw new RuntimeException(e);
} finally {
lock.unlock();
}
if (! isDone()) {
throw new TimeoutException(sent > 0, channel, getTimeoutMessage(false));
}
}
return returnFromResponse();
}
}这里的超时时间设置的是1s
public static final int DEFAULT_TIMEOUT = 1000;解决方案
检查消费者配置查看是否配置总的超时时长，这里建议配置一个总的，我由于没配置导致使用的是默认配置使得超过1s就报错。
<dubbo:consumer timeout="5000" />也可以在消费者端对每个服务自定义配置
<dubbo:reference interface="com.foo.BarService" timeout="2000"/>这里也需要注意服务端也有一个超时时间
- 全局配置
<dubbo:provider timeout="5000"/>- 服务配置
<dubbo:provider interface="com.foo.BarService" timeout="5000">当客户端timeout值>服务端timeout值，会出现超时日志，但是仍然可以获取到结果。客户端timeout超时抛出异常时，有一个线程RemotingInvocationTimeoutScan会自动清理对应超时的Future。
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