Finding memory leaks

Sat Feb 28 23:48:00 GMT 2004

On Sat, 2004年02月28日 at 20:35, Andrew Haley wrote:
> Does a trivial app (concatenate a ton of strings, throw a way the
> result, loop) collect OK for you? It does for me.

Unfortunately - at least in my case - trivial apps seem to always
behave as expected :-(
 
> I've been thinking about this. What we really need is a mode that
> prints out every object found during the sweep in such a way that you
> can see how everything has been reached.

Some good things for debugging (and that I'm missing in - hmh - some
very wide-spread JVMs, too :-)) were:
 - some (native) Java procedure that just returns a Vector/Enumeration
 with pointers to every object currently on the heap. This way a
 program can debug itself very easily and it's very simple to find
 memory leaks. It's not even very difficult to implement, I guess.
 I've always found Thread.enumerate() very useful for finding 
 looping or (dead-)locked threads. Something like 
 System.enumerateObjects() would serve equally well for debugging
 memory allocation problems.
 - boehm GC can be built with backtracing information being kept.
 This information would be very interesting - but it seems that
 gcj won't build with backtracing enabled(?). This is a pity ...
 - Maybe some of the effects I see are caused by incremental
 collection. If yes, some method of forcing the garbage collector
 into a non-incremental mode or - even better - of forcing one full
 none-incremental mark/sweep run on demand would make things much
 more transparent for debugging (just provided that System.gc() or
 GC_gcollect() doesn't do that, yet).
Best regards,
Tom
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If it's broke, fix it (The MS-DOS way). If it aint broke, don't touch
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