KeyboardFocusManager reason for memory leak?

Question

Hi all,
with a memory leak detector we found that our application has massive memory leaks after opening and closing a JDialog and the reason we found was the following:
The KeyboardFocusManager has a private static HashMap in which the actual focus in each window is stored. This is done by storing key/value-pairs in the HashMap with window as a key and the Component having the focus on this window as the value. Now you can throw the reference to the component away by using e.g. theComponent.setEnabled(false) - the KeyboardFocusManager then stores the pair window/null in the HashMap - but we didn't find any callable method to remove a key/value-pair from the HashMap and so the reference to the JDialog (as the key!!) stays resident and we have the reason for the memory leak. Now I have a few questions to this problem:
1. Is it right in your opinion, that there is no method to delete the entry from this Hashtable?
2. If this is the case - we have the opinion that there must be a good time to delete this entry (e.g. when disposing the dialog). Do you see if there is an obvious reason that this opinion is false?
3. If no do you think this problem can be accepted as a bug by sun
Thanks in advance and greetings from
Holger

Answer 1

I have been seeing similar behavior; I too have not found all the
leaks. I think I have slowed the allocation by replacing some of my
'build array' functions with the combination of 'initialize array'
followed by 'replace array subset'. The drawback to doing it this way
is that you have a fixed maximum number of elements allocated just once
rather than allowing an array to grow incrementally. Please let me know
if you try removing build arrays and if that helps.
By the way, there is a checkbox under the options menu to deallocate
memory as soon as possible - if you don't mind that your program runs
more slowly, this may help to avoid the problem, at least temporarily.
-vinny
ciossek wrote:
> dear all,
> my labview program needs an increasing amount of memo
ry when running
> (at the time about 12k/s) which leads to swapping memory on my hdd.
> i have found out that calling cluster references like Controls[] or
> decos[] leads to this kind of memory leak and made a work around for
> that (simply calling it only once at runtime) but there are more
> memory leak(s)which i cannot find. The bugs that i have found
> searching the labview resources does not answer my problem.
>
> does anybody already found out more memory leak problems ?
>
> thanks