AlreadyCommittedException：在执行 buildPage 之后但在从 PageInfo (HippoCMS) 写入响应之前已经提交了响应

Question

我们使用 REST 端点提供我们的 CMS (Hippo) 内容，我注意到间歇性发生的奇怪行为：

在一段时间不活动或服务器重新启动后第一次调用端点（例如，http://site.name/api/articles/）时，它会引发以下异常。如果页面第二次刷新，一切正常。

Throwable thrown during doFilter on request with URI: /site/fr-ca/api/articles/ and Query: nullResponse already committed after doing buildPage but before writing response from PageInfo.
[INFO] [talledLocalContainer] net.sf.ehcache.constructs.web.AlreadyCommittedException: Response already committed after doing buildPage but before writing response from PageInfo.
[INFO] [talledLocalContainer]   at net.sf.ehcache.constructs.web.filter.CachingFilter.doFilter(CachingFilter.java:220)
[INFO] [talledLocalContainer]   at net.sf.ehcache.constructs.web.filter.Filter.doFilter(Filter.java:86)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
[INFO] [talledLocalContainer]   at org.hippoecm.hst.container.XSSUrlFilter.doFilter(XSSUrlFilter.java:52)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
[INFO] [talledLocalContainer]   at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
[INFO] [talledLocalContainer]   at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.StandardContextValve.__invoke(StandardContextValve.java:106)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java)
[INFO] [talledLocalContainer]   at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.StandardHostValve.__invoke(StandardHostValve.java:142)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java)
[INFO] [talledLocalContainer]   at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
[INFO] [talledLocalContainer]   at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617)
[INFO] [talledLocalContainer]   at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
[INFO] [talledLocalContainer]   at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
[INFO] [talledLocalContainer]   at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
[INFO] [talledLocalContainer]   at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
[INFO] [talledLocalContainer]   at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1521)
[INFO] [talledLocalContainer]   at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1478)
[INFO] [talledLocalContainer]   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
[INFO] [talledLocalContainer]   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
[INFO] [talledLocalContainer]   at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
[INFO] [talledLocalContainer]   at java.lang.Thread.run(Thread.java:745)

罪魁祸首代码如下：

protected void doFilter(final HttpServletRequest request,
        final HttpServletResponse response, final FilterChain chain)
        throws AlreadyGzippedException, AlreadyCommittedException,
        FilterNonReentrantException, LockTimeoutException, Exception {
    if (response.isCommitted()) {
        throw new AlreadyCommittedException(
                "Response already committed before doing buildPage.");
    }
    logRequestHeaders(request);
    PageInfo pageInfo = buildPageInfo(request, response, chain);

    if (pageInfo.isOk()) {
        if (response.isCommitted()) {
            throw new AlreadyCommittedException(
                    "Response already committed after doing buildPage"
                            + " but before writing response from PageInfo.");
        }
        writeResponse(request, response, pageInfo);
    }
}

第 220 行是在 if(response.isCommitted()) {} 内抛出 AlreadyCommittedException() 的行，

这让我觉得服务器此时认为响应已经提交。我检查了我的代码，并且可以确认我没有执行任何“中间”提交或写入 servlet 的输出流。

但最烦人的是，它只发生在第一个页面调用时，如果我刷新页面，问题就消失了。

附加细节：我们有一个缓存过滤器，用于缓存页面并调用 CacheFilter：

public class WaPageCache extends SimpleCachingHeadersPageCachingFilter {

    @Override
    protected String calculateKey(HttpServletRequest httpRequest) {
        String simpleKey = super.calculateKey(httpRequest);
        final String requestURI = httpRequest.getRequestURI();
        final String key = requestURI.contains("/binaries/content") ? simpleKey : simpleKey + httpRequest.getHeader("Cookie");
        return key;
    }

    @Override
    protected CacheManager getCacheManager() {
        ClassLoader standardClassloader = Thread.currentThread().getContextClassLoader();
        URL url = null;
        if (standardClassloader != null) {
            url = standardClassloader.getResource("ehcache-web-caching.xml");
        }
        return CacheManager.create(url);
    }
}

有没有其他人遇到过类似的问题，可能的原因/解决方案/解决方案的提示是什么？

Answer 1

我找到了解决方法：在我的 web 应用程序中，我有几个过滤器，诀窍是将缓存过滤器放在所有其他过滤器之后（在我的 Hippo 案例中，特别是在 HstFilter 之后）。好吧，我有另一个过滤器来设置响应标头，并且可以在缓存过滤器之后使用。这是我更新的 web.xml 的片段：

      <filter-mapping>
        <filter-name>HstFilter</filter-name>
        <url-pattern>/*</url-pattern>
      </filter-mapping>

      <!-- This is my filter that was throwing the spanner -->
      <filter-mapping> 
        <filter-name>WaPageCache</filter-name>
        <url-pattern>/*</url-pattern>
      </filter-mapping>

      <filter-mapping>
        <filter-name>ApiResourceHeadersFilter</filter-name>
        <url-pattern>/api/site/*</url-pattern>
      </filter-mapping>