webflux - webclient Connect reset by peer Error

webflux - webclient Connect reset by peer Error

Connect reset by peer problem

Connection reset by peer The server is on the opposite side Socket It is caused by transferring data to the connection after it is closed , But the reason why the opposite end closes the connection is unknown

It can happen on the client side and the server side

Some common socket problem

abnormal	reason
java.net.BindException:Address already in use: JVM_Bind	This exception occurs on the server side new ServerSocket(port) In operation , The reason is that the local port has been occupied by other programs . Use at this time netstat –an command , You can see the ports that are already in use locally , Using an unoccupied port can solve this problem
java.net.ConnectException: Connection refused: connect	This exception occurs on the client side new Socket(ip, port) In operation , The reason is that the target cannot be found ip Server of address （ That is, from the current machine does not exist to the specified ip The routing ）, Or it's time to ip There is , But there is no program listening on the specified port on the target server
java.net.SocketException: Socket is closed	This exception may occur on both the client and the server , The reason is that after your side actively closes the connection （ Called Socket#close() Method ） Then read and write the network connection
java.net.SocketException: Connect reset by peer	The other is ,TCP Both ends have exchanged FIN The message closes the connection normally , But one end still uses the connection to read and write data
java.net.SocketException: Connection reset	Current end Socket Received the opposite RST The data is still read after the message
java.net.SocketException: Broken pipe	This exception can occur on both the client and the server , The front end is disconnected before reading and writing data （ For example, when the front-end program is ready to write data to Socket, Result initiation IO The program exits abnormally after calling ）, Then throw the exception

Online reasons

• reactor-netty The connection pool allocates threads reactor-http-epoll-1 Processing a request A,reactor-http-epoll-1 The processing process is slow SQL It has been blocked 60s, During this period, the same interface is accessed with high frequency , Other threads in the connection pool are also assigned to handle the same kind of requests , And then because it's slow SQL Block up . When the threads in the connection pool are blocked , New requests come , There are no threads in the connection pool to process it , Therefore, the requester has been hold, Until it shuts down after timeout Socket. After that, the server connection pool thread finally finished processing slowly SQL request , Then deal with the backlog of requests , After completion, send the data to the requester , But found that the connection has been closed , And then they reported Connection reset by peer error . The experience gained from this investigation is , If the service reports Connection reset by peer error , First, check whether there is a particularly slow action in the service that blocks the thread
• Article address : connect reset by peer

Solution

• Set as a short connection

  • public WebClient client() {
            
        if (webClient == null) {
            
            synchronized (lock) {
            
                if (webClient == null) {
            
                    ClientHttpConnector connector = new ReactorClientHttpConnector(HttpClient.create().keepAlive(false));
                    webClient = WebClient.builder().clientConnector(connector).baseUrl("svc-user").build();
                }
            }
        }
        return webClient;
    }
    

• Set timeout

  • ConnectionProvider provider = ConnectionProvider.builder("fixed")
        .maxConnections(500)
        .maxIdleTime(Duration.ofSeconds(20))
        .maxLifeTime(Duration.ofSeconds(60))
        .pendingAcquireTimeout(Duration.ofSeconds(60))
        .evictInBackground(Duration.ofSeconds(120)).build();
    
    this.webClient = WebClient.builder()
        .clientConnector(new ReactorClientHttpConnector(HttpClient.create(provider)))
        .build();
    

Connect reset problem

Connection reset The server is on the opposite side Socket` It is caused by reading data to the connection after it is closed , But the reason why the opposite end closes the connection is unknown

It can happen on the client side and the server side