Question

我正在开发一个使用activemq来交换消息的应用程序，有些很大，我想取消它。

我们使用activemq故障转移传输与两个ActiveMQ实例（主/从）。代理本身对消息有100mb的帧大小限制。

问题是：如果我尝试发送大于100mb的消息，ActiveMQ服务器将关闭连接。此时，故障转移传输将尝试重新连接并再次发送消息，从而创建无限循环。

客户端记录以下内容：

2017-01-05 09:19:11.910  WARN 14680 --- [0.1:61616@57025] o.a.a.t.failover.FailoverTransport       : Transport (tcp://localhost:61616) failed , attempting to automatically reconnect: {}

java.io.EOFException: null
    at java.io.DataInputStream.readInt(DataInputStream.java:392) ~[na:1.8.0_91]
    at org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:267) ~[activemq-client-5.13.4.jar:5.13.4]
    at org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:240) ~[activemq-client-5.13.4.jar:5.13.4]
    at org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:232) ~[activemq-client-5.13.4.jar:5.13.4]
    at org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:215) ~[activemq-client-5.13.4.jar:5.13.4]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_91]

2017-01-05 09:19:11.921  INFO 14680 --- [ActiveMQ Task-1] o.a.a.t.failover.FailoverTransport       : Successfully reconnected to tcp://localhost:61616
2017-01-05 09:19:11.923  WARN 14680 --- [0.1:61616@57026] o.a.a.t.failover.FailoverTransport       : Transport (tcp://localhost:61616) failed , attempting to automatically reconnect: {}

java.io.EOFException: null
    at java.io.DataInputStream.readInt(DataInputStream.java:392) ~[na:1.8.0_91]
    at org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:267) ~[activemq-client-5.13.4.jar:5.13.4]
    at org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:240) ~[activemq-client-5.13.4.jar:5.13.4]
    at org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:232) ~[activemq-client-5.13.4.jar:5.13.4]
    at org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:215) ~[activemq-client-5.13.4.jar:5.13.4]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_91]

activeMQ实例日志：

2017-01-05 09:19:11,909 | WARN  | Transport Connection to: tcp://127.0.0.1:57025 failed: java.io.IOException: Frame size of 363 MB larger than max allowed 100 MB | org.apache.activemq.broker.TransportConnection.Transport | ActiveMQ Transport: tcp:///127.0.0.1:57025@61616
2017-01-05 09:19:11,922 | WARN  | Transport Connection to: tcp://127.0.0.1:57026 failed: java.io.IOException: Frame size of 363 MB larger than max allowed 100 MB | org.apache.activemq.broker.TransportConnection.Transport | ActiveMQ Transport: tcp:///127.0.0.1:57026@61616

我尝试设置一个TransportListener来验证我是否可以捕获这种情况，但我只是收到一个transportInterupted事件，没有任何分类器。

我阅读了有关故障转移传输（http://activemq.apache.org/failover-transport-reference.html）的文档，也许我可以使用maxReconnectAttempts，但我知道在更常见的情况下我会有几个缺点（比如服务器暂时不可用）。

如何检测这种情况并避免客户端和服务器之间的无限连接循环？

Answer 1

正如你所说的那样

maxReconnectAttempts -1 | 0从ActiveMQ 5.6：默认为-1，永远重试。 0表示禁用重新连接，例如：尝试连接一次。在ActiveMQ之前 5.6：默认为0，永远重试。所有ActiveMQ版本：值> 0表示错误发生前的最大重新连接尝试次数送回客户端。

因此，如果由于邮件大小而导致重试失败后，您希望传输侦听器收到传输失败的通知，则需要将maxReconnectAttempts设置为值＆gt; 0之后，当最大重试次数到达方法时，将使用IOException作为参数调用传输侦听器的异常，但正如您所说，验证它是否是由于最大大小或其他问题而不容易。

如果要在发送之前检查消息大小，可以在运行时通过jmx访问它来获取在代理端的uri中配置的maxFrameSize，并获取BrokerViewMBean实例并调用getTransportConnectorByType方法{ {3}}这将返回在activemq.xml中配置的uri，您可以解析它以检索maxFrameSize。

JMXServiceURL url = new     JMXServiceURL("service:jmx:rmi:///jndi/rmi://hist:1099/jmxrmi");
JMXConnector jmxc = JMXConnectorFactory.connect(url);
MBeanServerConnection conn = jmxc.getMBeanServerConnection(); 

ObjectName activeMq = new ObjectName("org.apache.activemq:Type=Broker,BrokerName=localhost");

BrokerViewMBean mbean = (BrokerViewMBean)MBeanServerInvocationHandler.newProxyInstance(conn, activeMq, BrokerViewMBean.class, true);
String uri = mbean.getTransportConnectorByType("tcp");// or ("ssl") 
String[] pairs = uri.split("&");
for (String pair : pairs) {
    if (pair.startsWith("wireFormat.maxFrameSize")) {
        int idx = pair.indexOf("=");
        System.out.println(URLDecoder.decode(pair.substring(idx + 1), "UTF-8"));
    }
}

http://activemq.apache.org/maven/apidocs/src-html/org/apache/activemq/broker/jmx/BrokerViewMBean.html#line.304会将传输名称的地图作为键返回，将uri作为值返回

要获得更好的邮件大小，您可以这样做：

        OpenWireFormat opf = new OpenWireFormat();
        opf.setTightEncodingEnabled(true);
        ByteSequence tab = opf.marshal(message);
        System.out.println(tab.length);

您的公司必须是这样的：

import java.io.IOException;
import java.net.URLDecoder;
import java.util.HashMap;
import java.util.Map;

import javax.jms.Connection;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.management.MBeanServerConnection;
import javax.management.MBeanServerInvocationHandler;
import javax.management.ObjectName;
import javax.management.remote.JMXConnector;
import javax.management.remote.JMXConnectorFactory;
import javax.management.remote.JMXServiceURL;

import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.ActiveMQSession;
import org.apache.activemq.broker.jmx.BrokerViewMBean;
import org.apache.activemq.command.ActiveMQTextMessage;
import org.apache.activemq.openwire.OpenWireFormat;
import org.apache.activemq.transport.TransportFilter;
import org.apache.activemq.transport.TransportListener;
import org.apache.activemq.transport.failover.FailoverTransport;
import org.apache.activemq.util.ByteSequence;

public class SimpleSenderMaxSizeManager {

    private static Connection conn = null;
    private static boolean transportChanged;
    private static Long MAX_FRAME_SIZE;

    public static void main(String[] args) throws JMSException {
        try {
            SimpleSenderMaxSizeManager.updateMaxSize("host1");
            ActiveMQConnectionFactory cf = new ActiveMQConnectionFactory(
                    "failover:(tcp://host1:5670,tcp://host2:5671)?randomize=false");
            cf.setTransportListener(new TransportListener() {

                @Override
                public void transportResumed() {
                    if (transportChanged) {
                        transportChanged = false;
                        try {
                            SimpleSenderMaxSizeManager.updateMaxSize(null);
                        } catch (Exception e) {
                        }
                    }
                }

                @Override
                public void transportInterupted() {
                    transportChanged = true;
                }

                @Override
                public void onException(IOException error) {
                }

                @Override
                public void onCommand(Object command) {
                }
            });
            conn = cf.createConnection();
            ActiveMQSession session = (ActiveMQSession) conn.createSession(false,
                    ActiveMQSession.INDIVIDUAL_ACKNOWLEDGE);
            MessageProducer producer = session.createProducer(session.createQueue("TEST"));
            conn.start();
            ActiveMQTextMessage msg = (ActiveMQTextMessage) session.createTextMessage("test");
            OpenWireFormat opf = new OpenWireFormat();
            opf.setTightEncodingEnabled(true);
            ByteSequence tab = opf.marshal(msg);
            System.out.println(tab.length);
            if (tab.length >= MAX_FRAME_SIZE) {
                throw new RuntimeException(tab.length + ">=" + MAX_FRAME_SIZE);
            }
            producer.send(msg);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (conn != null) {
                try {
                    conn.close();
                } catch (Exception e) {
                }
            }
        }
    }

    protected static void updateMaxSize(String host) throws Exception {
        JMXConnector jmxc = null;
        try {
            String jmxHost = host;
            String scheme = null;
            if (conn == null) {
                scheme = "tcp";
            } else {
                org.apache.activemq.transport.TransportFilter responseCorrelator = (TransportFilter) ((ActiveMQConnection) conn)
                        .getTransport();
                TransportFilter mutexTransport = (TransportFilter) responseCorrelator.getNext();
                FailoverTransport failoverTransport = (FailoverTransport) mutexTransport.getNext();
                while (failoverTransport.getConnectedTransportURI() == null) {
                    try {
                        Thread.sleep(100);
                    } catch (Exception e) {
                    }
                }
                scheme = failoverTransport.getConnectedTransportURI().getScheme();
                jmxHost = failoverTransport.getConnectedTransportURI().getHost();
            }
            JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://" + jmxHost + ":1099/jmxrmi");
            Map<String, String[]> env = new HashMap<>();
            String[] creds = { "admin", "admin" };
            env.put(JMXConnector.CREDENTIALS, creds);
            jmxc = JMXConnectorFactory.connect(url, env);
            MBeanServerConnection conn = jmxc.getMBeanServerConnection();
            ObjectName activeMq = new ObjectName("org.apache.activemq:type=Broker,brokerName=localhost");
            BrokerViewMBean mbean = MBeanServerInvocationHandler.newProxyInstance(conn, activeMq, BrokerViewMBean.class,
                    true);
            String value = mbean.getTransportConnectorByType(scheme);
            String[] pairs = value.split("&");
            for (String pair : pairs) {
                if (pair.contains("wireFormat.maxFrameSize")) {
                    int idx = pair.indexOf("=");
                    System.out.println(URLDecoder.decode(pair.substring(idx + 1), "UTF-8"));
                    MAX_FRAME_SIZE = Long.valueOf(URLDecoder.decode(pair.substring(idx + 1), "UTF-8"));
                    MAX_FRAME_SIZE -= 1000;// security for JMS headers added by
                                            // session on sending
                }
            }
        } finally {
            if (jmxc != null) {
                try {
                    jmxc.close();
                } catch (Exception e) {
                }
            }
        }
    }
}

Answer 2

我不相信这是可能的。您正在尝试对错误处理进行分类，该异常不会通过故障转移：传输。如果超过最大客户端数量，则可能发生相同类型的异常。

在发送声音之前检查邮件大小，就像一个可行的选项。

尺码检查是否有理由不符合您的要求？

    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>

      <script type="text/javascript">

        function updateChat(){

          $.ajax({

            //TODO set localhost to the strato livechat file
            url: "http://localhost:8080/LiveChat/USB/code/php/groups/liveChat.php",
            type: "get",
            data: "msg_id="+$('#msg_id').val(),
            dataType: "json",
            success: function(response, status, http){

              $.each(response, function(index, item){

                $("#ChatBox").html("<div class='lead MessageOfPerson'> <div class='NameOfPerson'> <p>" + item.msg_sender + "</p> </div> </div> <div class='MessageText'> <p>" + item.group_msg + "</p> </div> <hr/>" + $('#ChatBox').html());


            $('#msg_id').val(item.msg_id);

          });
        },
        error: function(http, status, error){

          alert( 'Error updating chat, ' + error);

        }
      });

    }

    //auto update chat
    setInterval( updateChat, 2000 );

</script>

如何使用故障转移传输处理Activemq的最大帧大小异常

2 个答案: