CoyoteAdapter An exception

Question

I have receive this error in catalinaerror log file. I do not know what it is and my servelet and webpages where running fine for last few years.
Any suggestion????????
2004-09-02 14:19:10 CoyoteAdapter An exception or error occurred in the container during the request processing
java.lang.NullPointerException
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:164)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:601)
     at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
     at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
     at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
     at java.lang.Thread.run(Thread.java:536)
2004-09-02 14:19:10 CoyoteAdapter An exception or error occurred in the container during the request processing
java.lang.NullPointerException
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:164)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:601)
     at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
     at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
     at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
     at java.lang.Thread.run(Thread.java:536)

Answer 1

The project I'm working on first ran on tomcats under Windows, then on tomcats on Spars/Solaris and now on jboss servers with integrated tomcats, also running on Sparc/Solaris.
Using https mainly, we usually have about 400 concurrent user sessions open at a time.
On Windows, the tomcats usually crashed within three weeks of operation.
On Unix they can run for months.
So, unless you plan to use a clustered environment, I can only recommend using unix servers. Relying on a single Windows box is suicide.
There is a memory leak in the javac compiler, so if you keep compiling jsp files, your box will crash eventually.
I must say however, that I'm still suspicious. I started a jboss node 10 days ago and there are currently 544 threads running, most of them connector threads. The java runtime has allocated 720 MB memory and uses 270 MB of it.
It seems to me, that even the new Coyote Connectors use one thread per connection. Since the tomcat crew decided to build tomcat with JDK 1.4, I'm wondering, whether they will also start to use the nio capabilities soon. By using asynchronous IO mechanisms, the number of threads used could be reduced dramatically.
Currently, I do not see that connector threads get pruned at all.
All I see is that new ones get created. Yesterday, I disconnected the above mentioned jboss node from the cluster, but didn't shuit it down. Today it still has the same number of threads running, the same memory requirements.
This is not OK, of cause.
The tomcat developers themselves recommend to run tomcat behind an apache server for production environments. Personally, I admit that this could increase the overall stability but I refuse to do this nonetheless. I want to keep the non-java portion of our system as small as possible... ;)