Spring websockets Broken pipe & client not receiving messages

Question

I have a few problems with using websockets:

• java.io.IOException: Broken Pipe
• Client doesn't receive messages

  ---

  TL;DR

Main things I want to know:

• Please list all possible scenarios why the client side closes the connection (apart from refreshing or closing the tab).
• Can a Broken Pipe Exception occur, apart from the server sending a message to the client over a broken connection? If yes, then how?
• What are the possible scenarios why a server doesn't send a message, although the server does send heartbeats? (When this happens, I need to restart the application for it to work again. This is a terrible solution, because it already is in production.)

---

I have a SpringMVC project that uses websockets; SockJS client side and org.springframework.web.socket.handler.TextWebSocketHandler server side.

A JSON is generated server side and send to the client. Sometimes, I get a java.io.IOException: Broken Pipe. I googled/StackOverflowed a lot and found too many things I don't understand, but the reason is probably the connection is closed client side and the server still sends a message (for example, a heartbeat). Does this sound okay? What are other causes for this exception to arise? What are the reasons for the client side to close the connection (apart from refreshing or closing the tab)?

Also, sometimes the client side doesn't get any messages from the server, although the server should send them. I log before and after sending the message, and both log statements are printed. Does anyone has an idea why this can occur? I have no errors in the console log of Chrome. Refreshing the page doesn't work, I need to restart the spring project...

If you need more info, please leave a comment.

---

Client side

function connect() {
    var socket = new SockJS('/ws/foo');

    socket.onopen = function () {
        socket.send(fooId); // ask server for Foo with id fooId.
    };

    socket.onmessage = function (e) {
        var foo = JSON.parse(e.data);
        // Do something with foo.
    };
}

Server side
Service

@Service
public class FooService implements InitializingBean {
    public void updateFoo(...) {
        // Update some fields of Foo.
        ...
        // Send foo to clients.
        FooUpdatesHandler.sendFooToSubscribers(foo);
    }
}

WebSocketHandler

public class FooUpdatesHandler extends ConcurrentTextWebSocketHandler {
// ConcurrentTextWebSocketHandler taken from https://github.com/RWTH-i5-IDSG/BikeMan (Apache License version 2.0)

    private static final Logger logger = LoggerFactory.getLogger(FooUpdatesHandler.class);
    private static final ConcurrentHashMap<String, ConcurrentHashMap<String, WebSocketSession>> fooSubscriptions =
            new ConcurrentHashMap<>();

    public static void sendFooToSubscribers(Foo foo) {
        Map<String, WebSocketSession> sessionMap = fooSubscriptions.get(foo.getId());

        if (sessionMap != null) {
            String fooJson = null;
            try {
                fooJson = new ObjectMapper().writeValueAsString(foo);
            } catch (JsonProcessingException ignored) {
                return;
            }

            for (WebSocketSession subscription : sessionMap.values()) {
                try {
                    logger.info("[fooId={} sessionId={}] Sending foo...", foo.getId(), subscription.getId());
                    subscription.sendMessage(new TextMessage(fooJson));
                    logger.info("[fooId={} sessionId={}] Foo send.", foo.getId(), subscription.getId());
                } catch (IOException e) {
                    logger.error("Socket sendFooToSubscribers [fooId={}], exception:  ", foo.getId(), e);
                }
            }
        }
    }
}

Answer 1

Just an educated guess: Check your networking gear. Maybe there is a misconfigured firewall terminating these connections; or even worse, broken networking gear causing the connections to terminate. If your server has multiple NICs (which is likely the case), it's also possible that there is some misconfiguration using these NICs, or in connecting to the server via different NICs.