Websocket出現的錯誤

時間 2019-11-18

標籤 websocket 出現錯誤简体版

原文原文鏈接

前端使用sockjs，後臺使用spring的websocket框架html

結果在一個網絡較慢的地方，發現tomcat報錯信息：前端

Oct 28, 2015 10:10:43 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [mvc-dispatcher] in context with path [/rscc] threw exception [Request processing failed; nested exception is org.springframework.web.socket.sockjs.SockJsException: Uncaught failure in SockJS request, uri=http://xxx/user/854/qckzogtf/xhr_streaming; nested exception is org.springframework.web.socket.sockjs.SockJsException: Uncaught failure for request http://xxx/user/854/qckzogtf/xhr_streaming; nested exception is java.lang.IllegalArgumentException: Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "<async-supported>true</async-supported>" to servlet and filter declarations in web.xml. Also you must use a Servlet 3.0+ container] with root cause
java.lang.IllegalArgumentException: Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "<async-supported>true</async-supported>" to servlet and filter declarations in web.xml. Also you must use a Servlet 3.0+ container
    at org.springframework.util.Assert.isTrue(Assert.java:65)
    at org.springframework.http.server.ServletServerHttpAsyncRequestControl.<init>(ServletServerHttpAsyncRequestControl.java:59)
    at org.springframework.http.server.ServletServerHttpRequest.getAsyncRequestControl(ServletServerHttpRequest.java:202)
    at org.springframework.web.socket.sockjs.transport.session.AbstractHttpSockJsSession.initRequest(AbstractHttpSockJsSession.java:238)
    at org.springframework.web.socket.sockjs.transport.session.AbstractHttpSockJsSession.handleInitialRequest(AbstractHttpSockJsSession.java:203)
    at org.springframework.web.socket.sockjs.transport.session.StreamingSockJsSession.handleInitialRequest(StreamingSockJsSession.java:54)
    at org.springframework.web.socket.sockjs.transport.handler.AbstractHttpSendingTransportHandler.handleRequestInternal(AbstractHttpSendingTransportHandler.java:66)
    at org.springframework.web.socket.sockjs.transport.handler.AbstractHttpSendingTransportHandler.handleRequest(AbstractHttpSendingTransportHandler.java:58)
    at org.springframework.web.socket.sockjs.transport.TransportHandlingSockJsService.handleTransportRequest(TransportHandlingSockJsService.java:254)
    at org.springframework.web.socket.sockjs.support.AbstractSockJsService.handleRequest(AbstractSockJsService.java:317)
    at org.springframework.web.socket.sockjs.support.SockJsHttpRequestHandler.handleRequest(SockJsHttpRequestHandler.java:88)
    at org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter.handle(HttpRequestHandlerAdapter.java:51)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

根據報錯信息來看，應該是缺乏了<async-supported>true</async-supported>這個配置，這個是3.0開始支持的，async的請求須要開啓async-supported。java

可是該項目在咱們本地歷來沒有出現過這個問題，狀況說明及解決分析過程以下：web

1、前端鏈接狀況：ws = new SockJS( 'url', undefined, {});spring

　　不加參數，sockjs默認會選擇最優方式來鏈接，狀況以下：apache

　　關於協議選擇：在第一種鏈接方式超時時，sockjs會選擇次優方式進行鏈接：json

var _all_protocols = ['websocket',
                      'xdr-streaming',
                      'xhr-streaming',
                      'iframe-eventsource',
                      'iframe-htmlfile',
                      'xdr-polling',
                      'xhr-polling',
                      'iframe-xhr-polling',
                      'jsonp-polling'];
全部協議（鏈接方式）

　　檢測全部可用協議並按優先級排序tomcat

utils.probeProtocols = function() {
    var probed = {};
    for(var i=0; i<_all_protocols.length; i++) {
        var protocol = _all_protocols[i];
        // User can have a typo in protocol name.
        probed[protocol] = SockJS[protocol] &&
                           SockJS[protocol].enabled();
    }
    return probed;
};

utils.detectProtocols = function(probed, protocols_whitelist, info) {
    var pe = {},
        protocols = [];
    if (!protocols_whitelist) protocols_whitelist = _all_protocols;
    for(var i=0; i<protocols_whitelist.length; i++) {
        var protocol = protocols_whitelist[i];
        pe[protocol] = probed[protocol];
    }
    var maybe_push = function(protos) {
        var proto = protos.shift();
        if (pe[proto]) {
            protocols.push(proto);
        } else {
            if (protos.length > 0) {
                maybe_push(protos);
            }
        }
    }

    // 1. Websocket
    if (info.websocket !== false) {
        maybe_push(['websocket']);
    }

    // 2. Streaming
    if (pe['xhr-streaming'] && !info.null_origin) {
        protocols.push('xhr-streaming');
    } else {
        if (pe['xdr-streaming'] && !info.cookie_needed && !info.null_origin) {
            protocols.push('xdr-streaming');
        } else {
            maybe_push(['iframe-eventsource',
                        'iframe-htmlfile']);
        }
    }

    // 3. Polling
    if (pe['xhr-polling'] && !info.null_origin) {
        protocols.push('xhr-polling');
    } else {
        if (pe['xdr-polling'] && !info.cookie_needed && !info.null_origin) {
            protocols.push('xdr-polling');
        } else {
            maybe_push(['iframe-xhr-polling',
                        'jsonp-polling']);
        }
    }
    return protocols;
}

　　鏈接時若超時切換協議的代碼websocket

while(1) {
        var protocol = that.protocol = that._protocols.shift();
        if (!protocol) {
            return false;
        }
        // Some protocols require access to `body`, what if were in
        // the `head`?
        if (SockJS[protocol] &&
            SockJS[protocol].need_body === true &&
            (!_document.body ||
             (typeof _document.readyState !== 'undefined'
              && _document.readyState !== 'complete'))) {
            that._protocols.unshift(protocol);
            that.protocol = 'waiting-for-load';
            utils.attachEvent('load', function(){
                that._try_next_protocol();
            });
            return true;
        }
//下面的to = 就是計算鏈接超時時間的，調用delay，在鏈接超時時關閉這個協議的鏈接。
        if (!SockJS[protocol] ||
              !SockJS[protocol].enabled(that._options)) {
            that._debug('Skipping transport:', protocol);
        } else {
            var roundTrips = SockJS[protocol].roundTrips || 1;
            var to = ((that._options.rto || 0) * roundTrips) || 5000;
            that._transport_tref = utils.delay(to, function() {
                if (that.readyState === SockJS.CONNECTING) {
                    // I can't understand how it is possible to run
                    // this timer, when the state is CLOSED, but
                    // apparently in IE everythin is possible.
                    that._didClose(2007, "Transport timeouted");
                }
            });

            var connid = utils.random_string(8);
            var trans_url = that._base_url + '/' + that._server + '/' + connid;
            that._debug('Opening transport:', protocol, ' url:'+trans_url,
                        ' RTO:'+that._options.rto);
            that._transport = new SockJS[protocol](that, trans_url,
                                                   that._base_url);
            return true;
        }
    }

　　觀察上面報錯信息中的uri：uri=http://xxx/user/854/qckzogtf/xhr_streaming; 由於正常狀況下鏈接爲websocket鏈接，這個uri應該爲ws=http://xxx/user/854/qckzogtf/websocket，因而可知，這裏應該是切換爲xhr_streaming協議了cookie

　　前面也說過，他們網絡環境較慢，因此纔想，應該是鏈接超時致使的，有上面可知，to爲超時時間，計算公式爲

　　 var to = ((that._options.rto || 0) * roundTrips) || 5000;

　　關鍵在於that._options.rto，這個是new的時候的設置項，因此能夠設置rto超時長一點。

　　結果發現設置中只有

　　that._options = {devel: false, debug: false, protocols_whitelist: [],info: undefined, rtt: undefined};

　　這幾項，並無rto，因而繼續看

var SockJS = function(url, dep_protocols_whitelist, options) {
    if (this === _window) {
        // makes `new` optional
        return new SockJS(url, dep_protocols_whitelist, options);
    }
    
    var that = this, protocols_whitelist;
    that._options = {devel: false, debug: false, protocols_whitelist: [],
                     info: undefined, rtt: undefined};
    if (options) {
        utils.objectExtend(that._options, options);
    }
    that._base_url = utils.amendUrl(url);
    that._server = that._options.server || utils.random_number_string(1000);
    if (that._options.protocols_whitelist &&
        that._options.protocols_whitelist.length) {
        protocols_whitelist = that._options.protocols_whitelist;
    } else {
        // Deprecated API
        if (typeof dep_protocols_whitelist === 'string' &&
            dep_protocols_whitelist.length > 0) {
            protocols_whitelist = [dep_protocols_whitelist];
        } else if (utils.isArray(dep_protocols_whitelist)) {
            protocols_whitelist = dep_protocols_whitelist
        } else {
            protocols_whitelist = null;
        }
        if (protocols_whitelist) {
            that._debug('Deprecated API: Use "protocols_whitelist" option ' +
                        'instead of supplying protocol list as a second ' +
                        'parameter to SockJS constructor.');
        }
    }
    that._protocols = [];
    that.protocol = null;
    that.readyState = SockJS.CONNECTING;
    that._ir = createInfoReceiver(that._base_url);
    that._ir.onfinish = function(info, rtt) {
        that._ir = null;
        if (info) {
            if (that._options.info) {
                // Override if user supplies the option
                info = utils.objectExtend(info, that._options.info);
            }
            if (that._options.rtt) {
                rtt = that._options.rtt;
            }
            that._applyInfo(info, rtt, protocols_whitelist);
            that._didClose();
        } else {
            that._didClose(1002, 'Can\'t connect to server', true);
        }
    };
};

utils.objectExtend(that._options, options);這一句比較可疑是轉移屬性的，

that._applyInfo(info, rtt, protocols_whitelist);比較可疑，看一下

SockJS.prototype._applyInfo = function(info, rtt, protocols_whitelist) {
    var that = this;
    that._options.info = info;
    that._options.rtt = rtt;
    that._options.rto = utils.countRTO(rtt);
    that._options.info.null_origin = !_document.domain;
    var probed = utils.probeProtocols();
    that._protocols = utils.detectProtocols(probed, protocols_whitelist, info);
};

rto設置找到了！that._options.rto = utils.countRTO(rtt);

utils.countRTO = function (rtt) {
    var rto;
    if (rtt > 100) {
        rto = 3 * rtt; // rto > 300msec
    } else {
        rto = rtt + 200; // 200msec < rto <= 300msec
    }
    return rto;
}

好了，只用設置rtt既能夠設置rto了。。。就這樣，鏈接超時的問題算是解決了。

2、可是還沒完，就算websocket鏈接超時致使協議切換爲xhr_streaming，也不會致使後臺報錯的狀況出現，下面解決這個問題：

報錯處的代碼：在AbstractHttpSockJsSession類中：

private void initRequest(ServerHttpRequest request, ServerHttpResponse response,
            SockJsFrameFormat frameFormat) {

        Assert.notNull(request, "Request must not be null");
        Assert.notNull(response, "Response must not be null");
        Assert.notNull(frameFormat, "SockJsFrameFormat must not be null");

        this.response = response;
        this.frameFormat = frameFormat;
        this.asyncRequestControl = request.getAsyncRequestControl(response);
    }

最後一句報錯咯，看代碼：

public ServerHttpAsyncRequestControl getAsyncRequestControl(ServerHttpResponse response) {
        if (this.asyncRequestControl == null) {
            Assert.isInstanceOf(ServletServerHttpResponse.class, response);
            ServletServerHttpResponse servletServerResponse = (ServletServerHttpResponse) response;
            this.asyncRequestControl = new ServletServerHttpAsyncRequestControl(this, servletServerResponse);//這一句報錯了
        }
        return this.asyncRequestControl;
    }

new ServletServerHttpAsyncRequestControl時報錯

public ServletServerHttpAsyncRequestControl(ServletServerHttpRequest request, ServletServerHttpResponse response) {

        Assert.notNull(request, "request is required");
        Assert.notNull(response, "response is required");

        Assert.isTrue(request.getServletRequest().isAsyncSupported(),
                "Async support must be enabled on a servlet and for all filters involved " +
                "in async request processing. This is done in Java code using the Servlet API " +
                "or by adding \"<async-supported>true</async-supported>\" to servlet and " +
                "filter declarations in web.xml. Also you must use a Servlet 3.0+ container");

        this.request = request;
        this.response = response;
    }

　　最長那一句斷言報的錯，說的是web.xml的servlet和filter中要加入<async-supported>true</async-supported>

　　看下web.xml中，filter中確實沒有這一句，之因此必定要在filter中加入這一句，是由於websocket的切換協議請求，是經過filter攔截的，若是不在filter中配置async，則切換協議的請求將不是async的，因此上面就報錯了。

　　filter中加上以後，就行了。

　　若爲了讓controller也支持async則須要在dispatcher中這樣配置

<mvc:annotation-driven>
<!--  可不設置，使用默認的超時時間 -->
    <mvc:async-support default-timeout="3000"/>
</mvc:annotation-driven>

　　再返回上面initRequest方法，只有該類AbstractHttpSockJsSession的public void handleInitialRequest(ServerHttpRequest request, ServerHttpResponse response,SockJsFrameFormat frameFormat)方法與

public void handleSuccessiveRequest(ServerHttpRequest request,ServerHttpResponse response, SockJsFrameFormat frameFormat)中有調用，而調用這兩個方法的只有AbstractHttpSockJsSession的實現類：StreamingSockJsSession纔有，就是spring-websocket爲sockjs支持的xhr-streaming方式的實現類，而平時使用websocket的則是另一個實現類：

這就致使了以前一直沒有報錯，上了一個網絡較差的地方就報錯了，緣由分析完畢。

上面用的sockjs 0.3.4，最新的是1.0.3有所改變，可是大體相同

補充：相同個毛線，1.0.3的rtt再也不是經過參數傳進去的，而是計算出來的

function InfoAjax(url, AjaxObject) {
  EventEmitter.call(this);

  var self = this;
  var t0 = +new Date();
  this.xo = new AjaxObject('GET', url);

  this.xo.once('finish', function(status, text) {
    var info, rtt;
    if (status === 200) {
      rtt = (+new Date()) - t0;
      if (text) {
        try {
          info = JSON3.parse(text);
        } catch (e) {
          debug('bad json', text);
        }
      }

      if (!objectUtils.isObject(info)) {
        info = {};
      }
    }
    self.emit('finish', info, rtt);
    self.removeAllListeners();
  });
}

也就是說，超時時間控制不了的...什麼鬼

this._transportsWhitelist = options.transports;這個是設置白名單，優先使用這些方式。

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