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From Antonio Fiol Bonnín <fiol.bon...@terra.es>
Subject Re: Session Replication problems on Tomcat 5.0.12
Date Fri, 14 Nov 2003 20:26:58 GMT
Wait! That's a good one!

I am not sure whether that situation exists or not in the app. In fact, 
I don't see why it would be there, but...

Can't one store null as a value? Isn't this valid?

request.getSession().setAttribute("name",null);

About storing other classes, about a month ago I went through a thorough 
check of all our application to ensure that every setAttribute was 
executed with a Serializable parameter. Maybe one has slipped in since, 
but I doubt it: the relevant code has been very stable for about two months.

Apart from that, I'm afraid we are not catching the exception. You are 
giving me a lot of ideas to test on Monday morning.

Thank you very much.


Antonio Fiol


Filip Hanik wrote:

>when you get the exception, why don't you actually print out the attribute
>class,
>maybe you are storing null or another class under the same name elsewhere in
>your app
>----- Original Message -----
>From: "Antonio Fiol Bonnín" <fiol.bonnin@terra.es>
>To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
>Sent: Friday, November 14, 2003 11:53 AM
>Subject: Re: Session Replication problems on Tomcat 5.0.12
>
>
>Unfortunately, I cannot reproduce the error in a deterministic way. What
>I know is that it sometimes spits the exception. I use JMeter to stress
>the server a little bit, and the exception appears in localhost_log
>(does this help?). The app logs to catalina.out.
>
>What I mean is that it does not seem to me that it is the app catching
>the exception and printing to the log but maybe a tomcat thread on the
>receiving side (does that make sense?).
>
>Would the stack trace be helpful? I will have it available on Monday
>morning.
>
>Anyway, do you advise to try 5.0.14 for our matters or is it better to
>stay back on 5.0.12? I have just read about 5.0.14 proving "fairly
>stable and successful"  ;-)  (From Y. Shapira, about an hour ago)
>
>Thank you very much.
>
>Antonio Fiol
>
>
>Filip Hanik wrote:
>
>  
>
>>I can not reproduce the error that you have, although I ran 5.0.14Beta, but
>>the code is the same.
>>
>>Filip
>>
>>I created a JSP on my environment, that looks like this.
>>
>><%
>>request.getSession().setAttribute("test","test");
>>
>>%>
>>ok
>>
>>
>>Tomcat 1 spits out
>>
>>Nov 14, 2003 11:12:58 AM
>>org.apache.catalina.cluster.session.SimpleTcpReplicatio
>>nManager log
>>INFO: writeObject() storing session A8FD8BD50E14477CC57E3EBA6F9591B8
>>Nov 14, 2003 11:12:58 AM
>>org.apache.catalina.cluster.session.SimpleTcpReplicatio
>>nManager log
>>INFO:   storing attribute 'test' with value 'test'
>>Nov 14, 2003 11:12:58 AM org.apache.catalina.cluster.tcp.ReplicationValve
>>addClu
>>sterSendTime
>>INFO: Average cluster serialize/send time=16 ms for 1 requests (16ms).
>>
>>Tomcat 2 spits out
>>
>>Nov 14, 2003 11:12:58 AM
>>org.apache.catalina.cluster.session.SimpleTcpReplicatio
>>nManager log
>>INFO: Received SessionMessage of type=SESSION-MODIFIED
>>Nov 14, 2003 11:12:58 AM
>>org.apache.catalina.cluster.session.SimpleTcpReplicatio
>>nManager log
>>INFO: Received SessionMessage
>>sender=org.apache.catalina.cluster.mcast.McastMemb
>>er[tcp://10.0.2.76:4001,10.0.2.76,4001]
>>Nov 14, 2003 11:12:58 AM
>>org.apache.catalina.cluster.session.SimpleTcpReplicatio
>>nManager log
>>INFO: readObject() loading session A8FD8BD50E14477CC57E3EBA6F9591B8
>>Nov 14, 2003 11:12:58 AM
>>org.apache.catalina.cluster.session.SimpleTcpReplicatio
>>nManager log
>>INFO:   loading attribute 'test' with value 'test'
>>Nov 14, 2003 11:12:58 AM
>>org.apache.catalina.cluster.session.SimpleTcpReplicatio
>>nManager log
>>INFO: Received replicated session=ReplicatedSession
>>id=A8FD8BD50E14477CC57E3EBA6
>>F9591B8 ref=StandardSession[A8FD8BD50E14477CC57E3EBA6F9591B8]
>>       name=test; value=test
>>       LastAccess=1068837178625
>>
>>----- Original Message -----
>>From: "Antonio Fiol Bonnín" <fiol.bonnin@terra.es>
>>To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
>>Sent: Friday, November 14, 2003 10:51 AM
>>Subject: Re: Session Replication problems on Tomcat 5.0.12
>>
>>
>>Sorry. I forgot to mention that the attribute is, in fact, a String. And
>>Strings are, AFAICT, Serializable.
>>
>>Something like:
>>
>>String message = "Please use your XYZ user and pass";
>>session.setAttribute("authMessage", message);
>>// And then redirect to the auth page.
>>
>>The exception complains about "authMessage" not being Serializable.
>>
>>Sorry again about being imprecise, and thank you very much for your
>>really fast answer.
>>
>>
>>Antonio Fiol
>>
>>
>>Filip Hanik wrote:
>>
>>
>>
>>    
>>
>>>>What we get is an exception saying that some attribute is not
>>>>
>>>>
>>>>        
>>>>
>>serializable.
>>
>>
>>    
>>
>>>>        
>>>>
>>>This is according to the servlet spec.
>>>
>>>All your attributes have to be serializable, if you want to cluster a
>>>
>>>
>>>      
>>>
>>webapp
>>
>>
>>    
>>
>>>Filip
>>>----- Original Message -----
>>>From: "Antonio Fiol Bonnín" <fiol.bonnin@terra.es>
>>>To: <tomcat-user@jakarta.apache.org>
>>>Sent: Friday, November 14, 2003 10:11 AM
>>>Subject: Session Replication problems on Tomcat 5.0.12
>>>
>>>
>>>Hello,
>>>
>>>I am having trouble with Tomcat 5.0.12 session replication under the
>>>following config:
>>>
>>>Apache (mod_ssl+mod_jk): 1 load balancer worker configured to balance
>>>among 3 AJP13 workers.
>>>3 Tomcat 5.0.12 servers.
>>>
>>>If I use our application on 1 TC5, all goes well. If I start 2 or 3 TC5,
>>>I start getting session replication problems. What we get is an
>>>exception saying that some attribute is not serializable. (I do not have
>>>the logs handy at the moment, as I am writing from home). It happens
>>>under load, but it also can happen with very light number of accesses.
>>>
>>>It usually appears (on our app) on a page that sets some session
>>>attributes and sends a redirect. Then the browser requests the
>>>redirected page, and an exception (the one mentioned before) occurs, and
>>>the browser is redirected to an error page, after setting some other
>>>attribute on the session. The error servlet cannot extract the
>>>attributes from the session either.
>>>
>>>I have just found a note on http://www.filip.net/tomcat/ saying that
>>>there has been some trouble with session replication and mod_jk on TC4.
>>>Do you know whether this issue may apply to TC 5.0.12?
>>>
>>>I also found a couple of somewhat related bugs, but I am clueless about
>>>the degree of relation: the exception did not look the same to me.
>>>
>>>I have tried useDirtyFlag="false" just in case there were "dirty
>>>kludges" with session management in our app. It did not help.
>>>
>>>I am thinking of using 5.0.14. Do you think it might help?
>>>
>>>Our setup corresponds closely with the description found on
>>>http://jakarta.apache.org/tomcat/tomcat-5.0-doc/cluster-howto.html
>>>
>>>I am sure I am doing something wrong, but I cannot figure what. I'll be
>>>thankful for any advice or pointer to the "right" document or source.
>>>
>>>Thank you very much for your help.
>>>
>>>Yours,
>>>
>>>
>>>Antonio Fiol
>>>
>>>
>>>
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>>>
>>>
>>>
>>>
>>>
>>>
>>>      
>>>
>>
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>>
>>
>>
>>
>>    
>>
>
>
>
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>
>
>  
>


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