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[java] Networking causing applet to crash

Started by Dogbert Apr 23, 2001 at 3:34 PM 2 replies 450+ views

Original Post

Apr 23, 2001 at 3:34 PM

This is the same game as I mentioned in the "screen update" post (I''ve cured the that problem now, thanks guys) but with a new problem! To recap: I''m developing a simple 2D top-down multiplayer Java game. Each player controls a tank that they use to shoot at other player''s tanks. I''m using the java.net.Socket class to send messages between players concerning the state of the game (e.g. where their tank is, its current speed, health level etc) through a central server program. My problem is that after about a minute of play the client program crashes (I''m developing on Solaris and using the KDE window manager which catches the crash and reports it as being a sigsegv fault). This problem does not occur if I run the game single player (i.e. not sending the messages across the network). I''m developing this using Java 1.1.6 (not Java 1.2 as it needs to run as an applet in Netscape) on Unix (Solaris, version 5.6 I think). Does anyone have any idea what could cause this kind of problem or a method of debugging this, I would be very grateful as its part of my university project and I''m running out of time. Thanks, Martyn (dogbert@madasafish.com)

bobbin

Apr 25, 2001 at 4:44 AM

Its always cunning to setup an error log (then just tail the file). Do:

    
String logFilename = "/path/to/log/error_log";
PrintStream log = new PrintStream( new FileOutputStream( logFilename, true ) );
System.setErr( log );
System.setOut( log );

...now all output should go to that log file.

lilspikey

Apr 27, 2001 at 4:18 AM

Sounds like a bug in the VM. You are probably best trying to track down what the last thing is that the client does before crashing (just put println''s everywhere). Then you''ll probably have to code around the bug.
Are you running the clients in appletviewer or in netscape?
If it''s in appletviewer bobbins method should work fine, just make sure you flush the output every once in a while.

Dogbert

Apr 27, 2001 at 9:06 AM

I think it is a bug in the JVM. I only get the error when it is running in AppletViewer on unix. It does not happen when using netscape on unix or in AppletViewer on Windows 98.

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