RMI stress...

[Arno Reper]

Hello,
Im searching and breaking my brain but...i don't understand where the problem is.
When I launch the app in stand-alone mode...no problem
When I launch the server...no problem
When I launch one client connected on the previous server...no problem
But...
When I launch a second client on the same server i got a NullPointerException. Do you know what the problem is? or could be?

Here is the full stack trace...
Thank you for your help
Arno

  
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at suncertify.db.DataFileAccess.persistContractorRecord(DataFileAccess.java:265)
at suncertify.db.Data.updateRecord(Data.java:151)
at suncertify.remote.DatabaseImpl.updateRecord(DatabaseImpl.java:88)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Unknown Source)
at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source)
at sun.rmi.server.UnicastRef.invoke(Unknown Source)
at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(Unknown Source)
at java.rmi.server.RemoteObjectInvocationHandler.invoke(Unknown Source)
at $Proxy1.updateRecord(Unknown Source)
at suncertify.gui.GuiController.book(GuiController.java:185)
at suncertify.gui.GuiController.bookEvent(GuiController.java:116)
at suncertify.gui.GuiController.notify(GuiController.java:95)
at suncertify.gui.BookingPanel$2.actionPerformed(BookingPanel.java:139)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
 

  

[Eamonn O'Connell]

That could really be anything. Have a look at your persistContractorRecord() method. See what is causing NPE and take it from there. It could be that your design is not suitable for concurrent threads...

[Arno Reper]

I tested it, it look thread-safe...so i don't think its coming from datafileaccess, i think its the rmi stuff that has a problem somewhere...
Maybe my fa�ade...it makes me crazy

ps : line 265 is synchronized(database)

the worst thing is that the file is modified...its just insane lool

[Mihai Radulescu]

Arno,

I think that your problem is on :
at suncertify.db.DataFileAccess.persistContractorRecord(DataFileAccess.java:265)

"line 265 is synchronized(database)" - the synchronized does not care about the null references.

Regards,
M

[Arno Reper]

Hello,
Im almost sure its not there...i think its a RMI problem
because of this
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

I follow my searches
Arno
Thanks for your help

[Barry Gaunt]

What's the value of the reference variable database just before you enter the synchronized block? If it is null go up the call stack checking its value as you go.

[Arno Reper]

Its not null because the database is the RandomAccessFile and after i get this exception the file is modified...thats the "funny" thing.

The NPE only happens when i try to write (update)to the file and that i have two clients connected to the server ( only one is sending a request... ). The search function is working well...
Arfgh...

Arno

[ May 01, 2007: Message edited by: Arno Reper ]

[Arno Reper]

The problem is :
when i connect to the server with one client it works normally...but when a second client connect, the first one and the second one have a NPE when I have to update the file...maybe is there something wrong with the server...
AAAAaaaah I am so noob with networking and RMI...(I m still a programmer student)

Arno

[Arno Reper]

Illumination...
Could it be that its because I don't use 'rmic' on my RemoteObject?
I thought I didn't need it with 5.0...So would it change something?

ps: I would do it later for Sun...

==>[EDIT] Noooop...its not the problem [ May 01, 2007: Message edited by: Arno Reper ]

==>[RE-EDIT] POOOWWWWAAAA I got that little damn well hidden bug !!!
YEEEEEEEEEEEEEEEEEEEEEEAAAAH...I'll finally sleep nice today...loool
Make me happy...

Arno

[ May 01, 2007: Message edited by: Arno Reper ]