JEE6长轮询WebServlet - 调用AsyncContext＃complete后的异常 [英] JEE6 Long Polling WebServlet - Exception after calling AsyncContext#complete
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问题描述
我试图实现长轮询，但是在调用AsyncContext.complete（）之后，我得到了一个来自Weld的异常： Warnung：在ServletRequestListener上调用requestDestroyed方法的错误org.jboss.weld.servlet.WeldListener
java.lang.NullPointerException $ b $在org.jboss.weld.context.AbstractBoundContext.deactivate（AbstractBoundContext.java:71）
at org.jboss.weld.context.http.HttpRequestContextImpl.deactivate（HttpRequestContextImpl.java:70）
at org.jboss.weld.servlet.WeldListener.requestDestroyed（WeldListener.java:154）
在org.apache.catalina.core.StandardContext.fireRequestDestroyedEvent（StandardContext.java:5261）
at org.apache.catalina.core.StandardHostValve.postInvoke（StandardHostValve.java:255）
at org。 apache.catalina.connector.CoyoteAdapter.doService（CoyoteAdapter.java:359）
at org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:260）
at com.sun.enterprise。 v3.serv ices.impl.ContainerMapper.service（ContainerMapper.java:188）
位于org.glassfish.grizzly.http.server.HttpHandler.runService（HttpHandler.java:191）
位于org.glassfish.grizzly。 http.server.HttpHandler.doHandle（HttpHandler.java:168）
在org.glassfish.grizzly.http.server.HttpServerFilter.handleRead（HttpServerFilter.java:189）
在org.glassfish.grizzly。 filterchain.ExecutorResolver $ 9.execute（ExecutorResolver.java:119）
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter（DefaultFilterChain.java:288）
at org.glassfish.grizzly.filterchain.DefaultFilterChain .executeChainPart（DefaultFilterChain.java:206）
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute（DefaultFilterChain.java:136）
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process（DefaultFilterChain .java：114）
at org.glassfish.grizzly.ProcessorExecutor.execute（ProcessorExecutor.java:77）
at org.glassfish.grizzly.nio.transport.T CPNIOTransport.fireIOEvent（TCPNIOTransport.java:838）
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent（AbstractIOStrategy.java:113）
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0（ WorkerThreadIOStrategy.java:115）
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access $ 100（WorkerThreadIOStrategy.java:55）
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy $ WorkerThreadRunnable.run（WorkerThreadIOStrategy .java：135）
at org.glassfish.grizzly.threadpool.AbstractThreadPool $ Worker.doWork（AbstractThreadPool.java:564）
at org.glassfish.grizzly.threadpool.AbstractThreadPool $ Worker.run（AbstractThreadPool .java：544）
at java.lang.Thread.run（Thread.java:744）
我的Servlet的外观如下：
@WebServlet（urlPatterns = {/ newmsg}，asyncSupported = true）
public class NewMessageNotifierLongPolling扩展HttpServlet {
p rivate static final Queue< AsyncContext> peers = new ConcurrentLinkedQueue（）;
public void notifyClientsAboutNewMessage（@Observes Message msg）{
for（final AsyncContext ac：peers）{
try {
final ServletOutputStream os = ac.getResponse（） .getOutputStream（）;
os.println（msg.getSubject（））;
ac.complete（）;
} catch（IOException ex）{
Logger.getLogger（NewMessageNotifierLongPolling.class.getName（））.log（Level.SEVERE，null，ex）;
}终于{
peers.remove（ac）;
@Override
保护无效doGet（HttpServletRequest请求，HttpServletResponse响应）抛出ServletException，IOException {
响应。的setContentType（MediaType.TEXT_PLAIN）;
response.setStatus（202）;
response.setHeader（Pragma，no-cache）;
response.setCharacterEncoding（UTF-8）;
response.flushBuffer（）;
final AsyncContext ac = request.startAsync（request，response）;
ac.setTimeout（35 * 1000）;
ac.addListener（new AsyncListener（）{
@Override $ b $ public void onComplete（AsyncEvent event）throws IOException {
peers.remove（ac）;
}
@Override
public void onTimeout（AsyncEvent event）throws IOException {
peers.remove（ac）;
}
@Override
public void onError（AsyncEvent event）throws IOException {
peers.remove（ac）;
}
@Override
public void onStartAsync（AsyncEvent event）抛出IOException {
}
}）;
peers.add（ac）;
$ div $解析方案到这个JIRA ，Weld 1.1.10中存在一个错误（存在于Tomcat 7.0.23和相关的JBoss服务器），这会导致Async servlet在对同一个servlet的请求之间丢失上下文。
升级您的Weld或JBoss版本可解决问题。
I am trying to implement long polling, however after calling AsyncContext.complete() I get an exception from Weld:
Warnung: Error invoking requestDestroyed method on ServletRequestListener org.jboss.weld.servlet.WeldListener
java.lang.NullPointerException
at org.jboss.weld.context.AbstractBoundContext.deactivate(AbstractBoundContext.java:71)
at org.jboss.weld.context.http.HttpRequestContextImpl.deactivate(HttpRequestContextImpl.java:70)
at org.jboss.weld.servlet.WeldListener.requestDestroyed(WeldListener.java:154)
at org.apache.catalina.core.StandardContext.fireRequestDestroyedEvent(StandardContext.java:5261)
at org.apache.catalina.core.StandardHostValve.postInvoke(StandardHostValve.java:255)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:359)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:744)
My Servlet looks as follows:
@WebServlet(urlPatterns = {"/newmsg"}, asyncSupported = true)
public class NewMessageNotifierLongPolling extends HttpServlet {
private static final Queue<AsyncContext> peers = new ConcurrentLinkedQueue();
public void notifyClientsAboutNewMessage(@Observes Message msg) {
for (final AsyncContext ac : peers) {
try {
final ServletOutputStream os = ac.getResponse().getOutputStream();
os.println(msg.getSubject());
ac.complete();
} catch (IOException ex) {
Logger.getLogger(NewMessageNotifierLongPolling.class.getName()).log(Level.SEVERE, null, ex);
} finally {
peers.remove(ac);
}
}
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType(MediaType.TEXT_PLAIN);
response.setStatus(202);
response.setHeader("Pragma", "no-cache");
response.setCharacterEncoding("UTF-8");
response.flushBuffer();
final AsyncContext ac = request.startAsync(request, response);
ac.setTimeout(35 * 1000);
ac.addListener(new AsyncListener() {
@Override
public void onComplete(AsyncEvent event) throws IOException {
peers.remove(ac);
}
@Override
public void onTimeout(AsyncEvent event) throws IOException {
peers.remove(ac);
}
@Override
public void onError(AsyncEvent event) throws IOException {
peers.remove(ac);
}
@Override
public void onStartAsync(AsyncEvent event) throws IOException {
}
});
peers.add(ac);
}
}
解决方案
According to this JIRA, there's a bug in Weld 1.1.10 ( present in Tomcat 7.0.23 and related JBoss servers) that causes the Async servlet to lose context between requests to the same servlet.
Upgrading either your Weld or JBoss versions resolves the issue
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