Known Problems/Issues

June 25, 2001

Please report any problems/bugs to the J-Sim Team. Thanks.

Method Matching in Jacl

(Jacl) When invoking a method of a Java object from Jacl, it does not correctly find the matched method if the method name is not unique and the methods of the same name have the same number of arguments. Before we are able to fix the problem, the best bet is to avoid the above situation.

Solution

Jacl1.2.6 has some fix and then we have modified the Jacl codes to make it better. Now, it should work for most cases without giving complete method signature.

VJ++ Debugger

Thread synchornization in J-Sim simulation runtime seems to be interfered with VJ++ debugging mode operations. Specifically, the main thread should be notified when an event thread is finished, however, if we debug an event thread step-by-step, the main thread is incorrectly notified by an unknown thread.

Solution

Need to further verify if the bug is ours or Microsoft's. Our codes seem to run well in normal runs though.VJ++)

Incompatible Bytecodes

The Java Compiler from Microsoft produces incompatible Java bytecodes with the JVM from Sun's JDK.

Solution

If codes are compiled with the MS compiler, then use jview. All in all, we recommend to use Sun's JDK1.3 or later for better performance and stability.

Performance/Stability of JVM

I encounter the out-of-memory exception or the entire system is hung after I run a not-so-big scenario.

Solution

For better performance and stability, we recommend to use Sun's JDK1.3 or later. In linux, IBM's JDK1.3 has better performance than Sun's linux port of JDK1.3.

Copy/paste in X windows

In X windows, the copy/paste operations does not work for the J-Sim terminal classes.

Answer

The J-Sim terminal class (drcl.ruv.Dterm) uses Java AWT system clipboard to perform the copy/paste operations. As of JDK1.3, Java system clipboard only interacts with XClipboard but not the mouse click that are used by most of the X11 applications. To make it work between Java and other applications, "Launch XClipboard, then select your X11 text. Paste it into an XClipboard view. Now select it again and you can now paste it into a Java app. The reverse direction also works. Note, though, that 1.2.2 has a good chance of dumping core after doing this more than once, and 1.3 has a smaller but still finite chance of dumping core. It's flakey enough that I avoid pasting between Java and native X11 at all." The above solution is posted in WWW by Joi Ellis, Software Engineer Aravox Technologies.