[Building Sakai] Quizz issue

[Biku Shrestha]

Let me further clarify this issue:

We have had ongoing problems with quizzes.

It seems that when we have a class taking a quiz with more than a small number of students (perhaps 20-30), then all sorts of problems arise.

Students report getting logged off, and results getting lost, and logging back in. The quizzes would sometimes go blank, and then log the student off.  After a few questions, Sakai gives a syntax error. Browser repeatedly logged students out. The questions disappears some items and shows a message: "Validation Error". Sometimes this happens after 20+ questions, going to the "next" question. Long delays when going to the next question; the times keeps running and the spinner moving, but no question for over a minute sometimes. Etc...  (These are from the student reports...).

We are on 9.2, planning to go to 10.0 soon.
Last time we had a bunch of problems we increased the JVM memory (6 GB), and things improved.

Any ideas or hints on this sort of problems, or diagnostics, or solutions? The error message in log is shown below.

Sep 20, 2014 10:02:16 AM org.apache.coyote.http11.AbstractHttp11Processor endRequest
SEVERE: Error finishing response
java.lang.NullPointerException
       at org.apache.coyote.http11.InternalNioOutputBuffer.flushBuffer(InternalNioOutputBuffer.java:243)
       at org.apache.coyote.http11.InternalNioOutputBuffer.endRequest(InternalNioOutputBuffer.java:128)
       at org.apache.coyote.http11.AbstractHttp11Processor.endRequest(AbstractHttp11Processor.java:1290)
       at org.apache.coyote.http11.Http11NioProcessor.process(Http11NioProcessor.java:360)
       at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
       at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1544)
       at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
       at java.lang.Thread.run(Thread.java:662)


Sep 20, 2014 10:02:39 AM org.apache.catalina.connector.CoyoteAdapter log
WARNING: Exception while attempting to add an entry to the access log
java.lang.StringIndexOutOfBoundsException: String index out of range: -795
       at java.lang.String.checkBounds(String.java:397)
       at java.lang.String.<init>(String.java:482)
       at org.apache.tomcat.util.buf.ByteChunk.toStringInternal(ByteChunk.java:505)
       at org.apache.tomcat.util.buf.StringCache.toString(StringCache.java:320)
       at org.apache.tomcat.util.buf.ByteChunk.toString(ByteChunk.java:496)
       at org.apache.tomcat.util.buf.MessageBytes.toString(MessageBytes.java:189)
       at org.apache.catalina.connector.Request.getRequestURI(Request.java:2178)
       at org.apache.catalina.valves.AccessLogValve$RequestElement.addElement(AccessLogValve.java:1567)
       at org.apache.catalina.valves.AccessLogValve.log(AccessLogValve.java:955)
       at org.apache.catalina.core.AccessLogAdapter.log(AccessLogAdapter.java:51)
       at org.apache.catalina.core.StandardEngine.logAccess(StandardEngine.java:371)
       at org.apache.catalina.connector.CoyoteAdapter.log(CoyoteAdapter.java:508)
       at org.apache.coyote.http11.Http11NioProcessor.process(Http11NioProcessor.java:348)
       at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
       at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1544)
       at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
       at java.lang.Thread.run(Thread.java:662)

Thank you.

Biku

From: Biku Shrestha
Sent: Sunday, September 21, 2014 11:10 PM
To: 'sakai-user at collab.sakaiproject.org'
Cc: 'sakai-dev at collab.sakaiproject.org'
Subject: Quizz issue

Hi,

We have Sakai 2.9.2. We are experiencing some issues with the quizzes.


1.       For some students, the quiz page is blank

2.       For others: after couple of questions, they get syntax error message on the screen.

I checked the logs and found following errors:

Any ideas?

Thank you.
Biku

Sep 20, 2014 10:02:16 AM org.apache.coyote.http11.AbstractHttp11Processor endRequest
SEVERE: Error finishing response
java.lang.NullPointerException
       at org.apache.coyote.http11.InternalNioOutputBuffer.flushBuffer(InternalNioOutputBuffer.java:243)
       at org.apache.coyote.http11.InternalNioOutputBuffer.endRequest(InternalNioOutputBuffer.java:128)
       at org.apache.coyote.http11.AbstractHttp11Processor.endRequest(AbstractHttp11Processor.java:1290)
       at org.apache.coyote.http11.Http11NioProcessor.process(Http11NioProcessor.java:360)
       at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
       at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1544)
       at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
       at java.lang.Thread.run(Thread.java:662)


Sep 20, 2014 10:02:39 AM org.apache.catalina.connector.CoyoteAdapter log
WARNING: Exception while attempting to add an entry to the access log
java.lang.StringIndexOutOfBoundsException: String index out of range: -795
       at java.lang.String.checkBounds(String.java:397)
       at java.lang.String.<init>(String.java:482)
       at org.apache.tomcat.util.buf.ByteChunk.toStringInternal(ByteChunk.java:505)
       at org.apache.tomcat.util.buf.StringCache.toString(StringCache.java:320)
       at org.apache.tomcat.util.buf.ByteChunk.toString(ByteChunk.java:496)
       at org.apache.tomcat.util.buf.MessageBytes.toString(MessageBytes.java:189)
       at org.apache.catalina.connector.Request.getRequestURI(Request.java:2178)
       at org.apache.catalina.valves.AccessLogValve$RequestElement.addElement(AccessLogValve.java:1567)
       at org.apache.catalina.valves.AccessLogValve.log(AccessLogValve.java:955)
       at org.apache.catalina.core.AccessLogAdapter.log(AccessLogAdapter.java:51)
       at org.apache.catalina.core.StandardEngine.logAccess(StandardEngine.java:371)
       at org.apache.catalina.connector.CoyoteAdapter.log(CoyoteAdapter.java:508)
       at org.apache.coyote.http11.Http11NioProcessor.process(Http11NioProcessor.java:348)
       at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
       at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1544)
       at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
       at java.lang.Thread.run(Thread.java:662)

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