Background activity crashs. Why?

[Former Member]

Hi all,

we have an Web Dynpro for Java application running on a SAP WAS 7.00 EhP1 (7.01). Very often there are these errors in the logs but no user is complaining. Thus I think it is an background activity. There were no background activities programmed.

Since there are only SAP classes mentioned in the stacktrace, I think it is an error on the SAP side. Maybe someone has a hint to an OSS note ...

Exception occured during processing of Web Dynpro application xxx. The causing exception is nested.

[EXCEPTION]

java.lang.NullPointerException

at com.sap.tc.webdynpro.clientimpl.html.client.HtmlClient.cleanup(HtmlClient.java:119)

at com.sap.tc.webdynpro.clientserver.cal.AbstractClient.finishTasks(AbstractClient.java:194)

at com.sap.tc.webdynpro.clientserver.session.ApplicationSession.doProcessing(ApplicationSession.java:347)

at com.sap.tc.webdynpro.clientserver.session.ClientSession.doApplicationProcessingStandalone(ClientSession.java:742)

at com.sap.tc.webdynpro.clientserver.session.ClientSession.doApplicationProcessing(ClientSession.java:694)

at com.sap.tc.webdynpro.clientserver.session.ClientSession.doProcessing(ClientSession.java:253)

at com.sap.tc.webdynpro.clientserver.session.RequestManager.doProcessing(RequestManager.java:185)

at com.sap.tc.webdynpro.serverimpl.defaultimpl.DispatcherServlet.doContent(DispatcherServlet.java:62)

at com.sap.tc.webdynpro.serverimpl.defaultimpl.DispatcherServlet.doGet(DispatcherServlet.java:46)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)

at com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl.runServlet(HttpHandlerImpl.java:401)

at com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl.handleRequest(HttpHandlerImpl.java:266)

at com.sap.engine.services.httpserver.server.RequestAnalizer.startServlet(RequestAnalizer.java:386)

at com.sap.engine.services.httpserver.server.RequestAnalizer.startServlet(RequestAnalizer.java:364)

at com.sap.engine.services.httpserver.server.RequestAnalizer.invokeWebContainer(RequestAnalizer.java:1060)

at com.sap.engine.services.httpserver.server.RequestAnalizer.handle(RequestAnalizer.java:265)

at com.sap.engine.services.httpserver.server.Client.handle(Client.java:95)

at com.sap.engine.services.httpserver.server.Processor.request(Processor.java:175)

at com.sap.engine.core.service630.context.cluster.session.ApplicationSessionMessageListener.process(ApplicationSessionMessageListener.java:33)

at com.sap.engine.core.cluster.impl6.session.MessageRunner.run(MessageRunner.java:41)

at com.sap.engine.core.thread.impl3.ActionObject.run(ActionObject.java:37)

at java.security.AccessController.doPrivileged(Native Method)

at com.sap.engine.core.thread.impl3.SingleThread.execute(SingleThread.java:104)

at com.sap.engine.core.thread.impl3.SingleThread.run(SingleThread.java:176)

Thanks in advance!

[junwu · Accepted solution]

An attempt to write after the stream had been closed.

it is normal, when server is sending your something, you close the window, the connection is lost,  that error happens

[Former Member · Accepted solution]

That is a good answer but unsatisfying. That means all these errors are normal.

Thank you very much!

[ErvinSzolke · Accepted solution]

Hi Richard,

I think Jun is right. The server sends the response back to the client (the end user's browser) but the client has been closed in the meantime so the response cannot reach it and this gets logged on the server side, so I believe you can ignore it.

Regards,

Ervin

[Former Member · Accepted solution]

The server sends the response back to the client (the end user's browser) but the client has been closed in the meantime so the response cannot reach it and this gets logged on the server side...

Fully agree with and you.

...so I believe you can ignore it.

Not sure you are right. NullPointerException in HtmlClient.cleanup method? What it performs in cleanup method that lead to NullPointerException? It seems SAP need to perfrom some corrections in code. Would appreciate for your comments.

[ErvinSzolke · Accepted solution]

Hi,

could you please check whether the latest SAPJTECHS and SAPJTECHF patch levels have been applied ? Afaik there was a fix made recently in htmlclient.cleanup.

But I agree that however the "An attempt to write after the stream had been closed." is expected, the NPE (like in the inital post) is not.

Regards,

Ervin

[Former Member · Accepted solution]

Thank you Ervin,

do you have a SAP note for that fix? Since the server is not maintained by me (or direct contacts), I dont know about the latest fixes.

But good hint, the server was patched recently to 7.01 (before 7.00 SP14) but the NWDI is still thinking of an 7.00 server, so the SCA-files for building are still the 7.00 ones. The CBS builds with these SCAs. Maybe there is an incompatibility.

Again that horrible journey for these SCA-files ...

[ErvinSzolke · Accepted solution]

Hi,

I am not sure there is a note about that, but if you tell me the exact SP I let you know where to find the latest patch levels of the mentioned SCs.

Regarding NWDI I don't fully understand how this is related to the error "An attempt to write after the stream had been closed". The NWDI framework (i.e. SCs DI_*) and the content (i.e. the build plugins of a track) are different things. If you raise the Release/SP/patch of the server where NWDI resides then the build plugins inside the tracks won't be involved.

Here you can read about this more:

Developing for multiple releases with NWDI

http://scn.sap.com/thread/1775010

BUT: since this is getting a bit more NWDI related I rather suggest to post follow up questions under NWDI Forum: http://scn.sap.com/community/nwdi

Thanks and Regards, 😉

Ervin

[Former Member · Accepted solution]

I was just "mumbling" to myself. The point is that the NWDI is compiling for NW 7.00 SP22 but the actual runtime systems are 7.01 SP??. In detail I have provided the necessary libraries (SCA) to the NWDI for NW7.00. I anticipate that these library are (also) responsible for translating the WebDynpro-source files (XML with embedded Java code) to .java-files which are compiled afterwards.

If that does not match there might be incompatibilities. As I said before: good hint! Thanks!

[Former Member]

Can you attach full log file?

[Former Member]

The full log (default.trc) is quite big (lots of MB) but here are the next few entries :

error	30.10.2013	16:23:36:980	application [webdynpro/dispatcher] Cannot send an HTTP error response [500 Application error occurred during request processing. (details: java.lang.NullPointerException: null)]. The error is: com.sap.engine.services.servlets_jsp.server.exceptions.WebIOEx The error is: com.sap.engine.services.servlets_jsp.server.exceptions.WebIOException: An attempt to write after the stream... [siehe Details]	/System/Server/WebRequests	com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl	sap.com/tc~wd~dispwda
error	30.10.2013	16:23:36:980	application [webdynpro/dispatcher] Cannot send an HTTP error response [500 Application error occurred during request processing. (details: java.lang.NullPointerException: null)]. The error is: com.sap.engine.services.servlets_jsp.server.exceptions.WebIOException: An attempt to write after the streamhad... [siehe Details]	n/a	com.sap.engine.services.servlets_jsp.client.RequestInfoServer	sap.com/tc~wd~dispwda
error	30.10.2013	16:23:36:980	application [webdynpro/dispatcher] Cannot send an HTTP error response [500 Application error occurred during request processing. (details: java.lang.NullPointerException: null)].	/System/Server/WebRequests	com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl	sap.com/tc~wd~dispwda
			The error is: com.sap.engine.services.servlets_jsp.server.exceptions.WebIOException: An attempt to write after the stream... [siehe Details]
error	30.10.2013	16:23:36:980	application [webdynpro/dispatcher] Cannot send an HTTP error response [500 Application error occurred during request processing. (details: java.lang.NullPointerException: null)].	/System/Server/WebRequests	com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl	sap.com/tc~wd~dispwda
			The error is: com.sap.engine.services.servlets_jsp.server.exceptions.WebIOException: An attempt to write after the stream... [siehe Details]
error	30.10.2013	16:23:36:979	An exception "java.lang.NullPointerException" has occured during application processing. During exception handling, an additional exception "com.sap.tc.webdynpro.services.exceptions.WDRuntimeException: An attempt to write after the stream had been closed." was thrown. Both exception has been writtento... [siehe Details]	/System/UserInterface	com.sap.tc.webdynpro.sessionmanagement.ExceptionHandler.handleThrowable	sap.com/tc~wd~dispwda
error	30.10.2013	16:23:36:979	application [webdynpro/dispatcher] Processing HTTP request to servlet [dispatcher] finished with error.	/System/Server/WebRequests	com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl	sap.com/tc~wd~dispwda
			The error is: java.lang.NullPointerException: null
			Exception id: [3C4A9272E3A8005C00000BE600007C7B0004E9F6EAC700C6]
error	30.10.2013	16:23:36:979	application [webdynpro/dispatcher] Processing HTTP request to servlet [dispatcher] finished with error. The error is: java.lang.NullPointerException	n/a	com.sap.engine.services.servlets_jsp.client.RequestInfoServer	sap.com/tc~wd~dispwda
			at com.sap.tc.webdynpro.clientimpl.html.client.HtmlClient.cleanup(HtmlClient.java:119)
			at com.sap.tc.webdynpro.clientserver.cal.AbstractClient.fini... [siehe Details]
error	30.10.2013	16:23:36:979	An exception "java.lang.NullPointerException" has occured during application processing. During exception handling, an additional exception "com.sap.tc.webdynpro.services.exceptions.WDRuntimeException: An attempt to write after the stream had been closed." was thrown. Both exception has been writtento... [siehe Details]	/System/UserInterface	com.sap.tc.webdynpro.sessionmanagement.ExceptionHandler.handleThrowable	sap.com/tc~wd~dispwda
error	30.10.2013	16:23:36:979	failed to render error page	n/a	com.sap.tc.webdynpro.clientimpl.html.client.HtmlUpdateClientPeer	sap.com/tc~wd~dispwda
error	30.10.2013	16:23:36:979	application [webdynpro/dispatcher] Processing HTTP request to servlet [dispatcher] finished with error.	/System/Server/WebRequests	com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl	sap.com/tc~wd~dispwda
			The error is: java.lang.NullPointerException: null
			Exception id: [3C4A9272E3A8005C00000BE600007C7B0004E9F6EAC700C6]
error	30.10.2013	16:23:36:979	application [webdynpro/dispatcher] Processing HTTP request to servlet [dispatcher] finished with error.	/System/Server/WebRequests	com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl	sap.com/tc~wd~dispwda
			The error is: java.lang.NullPointerException: null
			Exception id: [3C4A9272E3A8005C00000BE600007C7B0004E9F6EAC700C6]
error	30.10.2013	16:23:36:978	Exception occured during processing of Web Dynpro application xxx. The causing exception is nested.	/System/UserInterface	com.sap.tc.webdynpro.sessionmanagement.ExceptionHandler.handleThrowable	sap.com/tc~wd~dispwda
error	30.10.2013	16:23:36:978	Exception occured during processing of Web Dynpro application xxx. The causing exception is nested. [EXCEPTION] java.lang.NullPointerException... [siehe Details]	/System/UserInterface	com.sap.tc.webdynpro.sessionmanagement.ExceptionHandler.handleThrowable	sap.com/tc~wd~dispwda

The entries before are several minutes away, so they don't belong to the problem.