在使用ForkChannel时调用MembershipListener#viewAccepted时RpcDispatcher#callRemoteMethods不起作用

Question

在使用ForkChannel时调用MembershipListener#viewAccepted时，RpcDispatcher#callRemoteMethods不起作用。

我正在尝试将我的应用程序中使用的JGroups版本从2升级到4.1.0。应用程序使用MuxRpcDispatcher，因为它使用多个RpcDispatchers。mux包在版本4中已被弃用，我们正在尝试使用替代的分支堆栈。但是，当您在viewAccepted中执行RpcDispatcher时，处理会冻结。

在使用ForkChannel时调用MembershipListener#viewAccepted时，RpcDispatcher#callRemoteMethods不起作用。

channel = new JChannel();
channel.setReceiver(this);

if (channel.getProtocolStack().findProtocol(FORK.class) == null) {
    channel.getProtocolStack().addProtocol(new FORK());
}

forkChannel = new ForkChannel(channel, "fork", "fork");
dispatcher1 = new RpcDispatcher(forkChannel, new Boe1());

channel.connect("test");
forkChannel.connect("test");

在viewAccepted中调用RpcDispatcher。处理在此调用时停止。

@Override
public void viewAccepted(final View new_view) {
    LOGGER.info("viewAccepted:start");
    try {
        final MethodCall call = new MethodCall(Boe1.class.getMethod("boeee"));
        final RequestOptions options = new RequestOptions(ResponseMode.GET_ALL, 0, true, null);
        dispatcher1.callRemoteMethods(null, call, options);
    } catch (final Exception e) {
        e.printStackTrace();
    }
    LOGGER.info("viewAccepted:end");
}

下面是一个处于停止状态的线程转储。

"jgroups-10,test,IM9072-10017" #22 prio=5 os_prio=0 tid=0x000000002b4b5800 nid=0x2cf8 waiting on condition [0x000000002c84d000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x000000071b24ccd0> (a java.util.concurrent.CompletableFuture$Signaller)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    at java.util.concurrent.CompletableFuture$Signaller.block(CompletableFuture.java:1693)
    at java.util.concurrent.ForkJoinPool.managedBlock(ForkJoinPool.java:3323)
    at java.util.concurrent.CompletableFuture.waitingGet(CompletableFuture.java:1729)
    at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
    at org.jgroups.blocks.GroupRequest.access$7(GroupRequest.java:1)
    at org.jgroups.blocks.GroupRequest$$Lambda$135/1688803174.call(Unknown Source)
    at org.jgroups.blocks.GroupRequest.doAndComplete(GroupRequest.java:274)
    at org.jgroups.blocks.GroupRequest.waitForCompletion(GroupRequest.java:254)
    at org.jgroups.blocks.GroupRequest.waitForCompletion(GroupRequest.java:1)
    at org.jgroups.blocks.Request.execute(Request.java:52)
    at org.jgroups.blocks.MessageDispatcher.cast(MessageDispatcher.java:319)
    at org.jgroups.blocks.MessageDispatcher.castMessage(MessageDispatcher.java:251)
    at org.jgroups.blocks.RpcDispatcher.callRemoteMethods(RpcDispatcher.java:96)
    at ppp.network.JChannelRunner.viewAccepted(JChannelRunner.java:79)
    at org.jgroups.JChannel.invokeCallback(JChannel.java:917)
    at org.jgroups.JChannel.up(JChannel.java:759)
    at org.jgroups.stack.ProtocolStack.up(ProtocolStack.java:908)
    at org.jgroups.protocols.FORK.up(FORK.java:131)

有没有办法避免冻结？

Answer 1

你不应该在回调中阻塞，比如viewAccepted()！如果一定要调用RPC，那么可以异步调用(mode=GET_NONE)或带外调用(OOB)。您也可以在单独的线程中执行此操作。

详情请参见1。干杯,

1

Answer 2

您所犯的错误是您在JChannel上注册了一个视图侦听器，而不是在ForkChannel上。

这意味着viewAccepted()回调是在ForkChannel还没有视图时调用的，因此调用该方法将立即返回，因为此时还没有记录成员资格。

我对该行进行了注释，并添加了Dispatcher1.setMembership line ()，现在，示例代码可以工作了。干杯,

public class JChannelRunner extends ReceiverAdapter implements Closeable {
    public static class Boe1 {
        public void boeee() {System.out.println("boe-1");}
    }

    private final static Logger LOGGER = Logger.getLogger(JChannelRunner.class.getName());

    JChannel channel;
    ForkChannel forkChannel;
    RpcDispatcher dispatcher1;

    protected void start() throws Exception {
        channel = new JChannel();
        // channel.setReceiver(this);

        if (channel.getProtocolStack().findProtocol(FORK.class) == null) {
            channel.getProtocolStack().addProtocol(new FORK());
        }

        forkChannel = new ForkChannel(channel, "fork", "fork");
        dispatcher1 = new RpcDispatcher(forkChannel, new Boe1());
        dispatcher1.setMembershipListener(this);
        channel.connect("test");
        forkChannel.connect("test");
    }

    public JChannelRunner() throws Exception {}

    public static void main(final String[] args) throws IOException, Exception {
        try (JChannelRunner runner = new JChannelRunner()) {
            runner.start();
            Thread.sleep(60 * 1000);
        }
    }

    @Override
    public void close() throws IOException {
        Util.close(dispatcher1, forkChannel, channel);
    }

    @Override
    public void viewAccepted(final View new_view) {
        LOGGER.info("viewAccepted:start");
        try {
            final MethodCall call = new MethodCall(Boe1.class.getMethod("boeee"));
            final RequestOptions options = new RequestOptions(ResponseMode.GET_ALL, 0, true, null);
            dispatcher1.callRemoteMethods(null, call, options);
        } catch (final Exception e) {
            e.printStackTrace();
        }
        LOGGER.info("viewAccepted:end");
    }
}