Name: md23716 Date: 10/22/99
We are expecting to ship JavaHelp with IBM SecureWay Host Publisher
V2.0. In the process of testing it, we have come across the following problem.
If you select an item on the table of contents navigation tree on the
left-hand side of the JavaHelp window, then use the page up and down keys to move
up and down the tree a number of times
(a dozen or so), you begin getting NullPointerExceptions in the Java
console and eventually the java.exe process pins CPU utilization at 100%.
It doesn't recover unless you kill the process.
With the test case I was able to recreate the problem, by both using the page up
and page down kwys as well as the up and down arrow keys.
Initilaly I suspected that the problem was Swing related, as all of the Null Pointer Exceptions
occured in the Swing Libraries, but not neccesarily the same one all the time. I therefore
raised a defect with the Swing team in Austin. However after there initial investigation they
felt the problem is related to JavaHelp. Respone I received:-
"Using our latest Swing 1.1, I have generated three difference
NullPointerExceptions. And what is interesting, I have generated the most common
one using Swing 1.1.1. Therefore, I do not think this problem is fixed in Swing
1.1.1. Also, since using Swing 1.1.1 normally causes a Runtime error, I can
future suspect JavaHelp.
I think the basic problem is that the user changes help topics faster than the
help panel can display the text. Eventually, something gets corrupted in the
help panel and causes the NPE. The location of the most common NPE is in the
ComponentView class. In this case, the parent Container for the ComponentView is
null for some reason when they don't expect it to be. I tried putting a test for
null in and skipping the add() method that causes the NPE. In this case, I
started getting exceptions in the JIT. I suspect that this may be a threading
issue in JavaHelp. Since we don't have the code to examine, it's just a guess.
I believe that this problem should be reported to the Sun/JavaHelp. I think the
JavaHelp developers should investigate and determine if there is something they
can do for this situation."
I have downloaded the latest Swing 1.1.1 and JavaHelp 1.1 beta and tested with this,
but the problem still occurs.
*Testcase provided: Yes - will send as email attachment to partner contact
(Review ID: 96904)