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https://issues.apache.org/jira/browse/FELIX-5302?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15365958#comment-15365958
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Carsten Ziegeler commented on FELIX-5302:
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[~db82407] Thanks, that's great, would it be possible for you to check whether
org.apache.felix.http.base.internal.whiteboard.tracker.WhiteboardServiceTracker.addingService(WhiteboardServiceTracker.java:36)
is called twice with the same service in the bad case or just once?
> NPE using Http Whiteboard
> -------------------------
>
> Key: FELIX-5302
> URL: https://issues.apache.org/jira/browse/FELIX-5302
> Project: Felix
> Issue Type: Bug
> Components: HTTP Service
> Affects Versions: http.jetty-3.2.0
> Reporter: Derek Baum
> Attachments: http.jetty.bad.log, http.jetty.good.log
>
>
> I am getting this NPE about 50% of the time after reconfiguring my servlet
> (causing it to unregister and re-register):
> [org.apache.felix.http.jetty:3.2.0] Exception while processing request to
> /hello/sayHello
> java.lang.NullPointerException: null
> org.apache.felix.http.base.internal.handler.ServletHandler.handle(ServletHandler.java:85)
> org.apache.felix.http.base.internal.dispatch.InvocationChain.doFilter(InvocationChain.java:79)
> org.apache.felix.http.base.internal.dispatch.Dispatcher.dispatch(Dispatcher.java:124)
> org.apache.felix.http.base.internal.DispatcherServlet.service(DispatcherServlet.java:61)
> javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
> org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:845)
> org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:583)
> org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:224)
> org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1160)
> org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:511)
> org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
> org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1092)
> org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
> org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:213)
> org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
> org.eclipse.jetty.server.Server.handle(Server.java:518)
> org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:308)
> org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:244)
> org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:273)
> org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:95)
> org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93)
> org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceAndRun(ExecuteProduceConsume.java:246)
> org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:156)
> org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:654)
> org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:572)
> java.lang.Thread.run(Thread.java:745)
> The servlet uses the Http Whiteboard:
> @Component(
> property = {
> HttpWhiteboardConstants.HTTP_WHITEBOARD_SERVLET_PATTERN + "=/hello/sayHello",
> HttpWhiteboardConstants.HTTP_WHITEBOARD_RESOURCE_PATTERN +
> "=/hello/static/*",
> HttpWhiteboardConstants.HTTP_WHITEBOARD_RESOURCE_PREFIX + "=/static"})
> public class HelloWorldServlet extends HttpServlet implements Servlet {
> }
> About 50% of the time when I initially deploy the Servlet, I've noticed that
> ServletRegistry.addServlet() is called twice for the same servlet with the
> same serviceId.
> I don't know why this happens, but when it does it leads to the NPE above.
> The second addServlet() invokes addToInactiveList().
> The system works in this state, but it has a duplicate servlet handler in the
> inactive list.
> If the servlet is now reconfigured, causing it to unregister and re-register,
> we get the NPE above on the next request.
> This appears to be because ServletRegistry.removeServlet() fails to invoke
> "resolvers.remove(regHandler)", when the inactive list contains the argument
> ServletInfo.
> Alternatively, addServlet() should never allow a duplicate registration to be
> added to the inactive list.
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