Memory leak in java / forcing garbage collection for unused resource?

Is there any possibility in big programs if not designed properly for leakage of memory?
If say i forget to force garbage collection of unused resouces what will happen?
Even if i am forcing garbage collection how much assurity can be given to do so?
I need answers w.r.t typical programming examples if someone can provide i will be happy.
Or any useful link.
Thanks
Vijendra

Memory leaks are usually much related with C/C++ programming since in that language you have direct access to memory using pointers.
Now, in Java you do not have access to pointers, however you could still tie up your objects in a way that the garbage collection can not remove them.
Basically, the grabage collection will search all the object implementation, and see if they are referenced or not. If not it will free that memory. However if you, somehow in you code allow a reference to your object then the garbage collection will not displose of that object.
An example I can think of is when developing web applications. For example storing objects in the session will mean that you will have a reference to the object from the session, therefore the garbage collection will not free up the meomry taken by those objects untill the session has expired.
That is how I know it... at least that is how they tought it to me!
regards,
sim085

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Dinesh wrote:
Hi Slava Imeshev,
Thanks for immediate response. I agree JVM will do GC at specific interval. But,
I have found that , there is some difference in both of them. If you invoke "Force
Garbage Collection" explicitly, the graph will show the heap memory usage to baseline.
Where in, if you perform System.gc(). It won't make much difference.
Thus why, I want to know what is the code behind the "Force Garbage Collection"
button.
Thanks,
-Dinesh.
"Slava Imeshev" <[email protected]> wrote:
"Dinesh" <[email protected]> wrote in message news:406a8df4$[email protected]..
How can i schedule "Force Garbage Collection" to be done at every
week or daily?.
Can i automate this process instead of manually invoking the button?
GC is already done by JVM automatically.
Why would you want to "schedule" it?
Regards,
Slava Imeshev

Do you think JOptionPane dialogs force garbage collection afterwards?

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Howdy Folks- I wrote a server monitor in java, which I
was expecting to run for months at a time without
restarting. Apparently there is some slow memory leak
which results in an OutOfMemoryError after a few
weeks. It's in a production system, so I can't
readily add debug statements to the code, and the
OutOfMemoryError apparently screwed up the logging, so
I didn't get a stack trace in my logs, just an
"OutOfMemoryError" went to standard out.Are you even attempting to catch Errors? Catching Exceptions will not help with this. It should print the stack trace. When it OOMs it doesn't mess up what's already allocated, it just can't allocate more.
I'm assuming the problem lies in the code,
specifically probably some discarded reference that is
not being properly garbage collected? Most likely, there are references that are never being cleared in your code. Without seeing the code or at least having a better description, I don't think anyone here can help you. Can you set up a test senario and use an Optimizer to see what's going on?
I am using a
few different ArrayLists to store some historical
information, and I call clear() on these frequently.
Is there any known issue with ArrayList or HashMap
that the "clear()" method doesn't result in garbage
collection of the objects that were in it? Not that I know of, no. I doubt that is the problem.

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Hi,
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I am looking for a precise definition here...

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Another way: interning strings to the jvm can cause a memory leak, because once a string is interned, it is stuck there forever, even if all other references to the string are gone, and the string will never again be used.
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- Adam

Memory leak in java / forcing garbage collection for unused resource?

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