Memory leak on SunOne Web Server 6.1 on application reload

Question

Hi!
I am pretty sure that i have found a memory management problem in
SunOne Web Server 6.1 .
It started with an OutOfMemory error we got under heavy load . After
some profiling with Jprofiler i didn't find any memory leaks in the
application.Even under heavy load (generated by myself) i can't find
anything ,more, i can't reproduce the error! The memory usage is
about 20Mb and does not go up .
However it is pretty simple to see the following behavior:
[1] Restart the server (to have a clear picture) and wait a little for
memory usage to stabilize.
[2] In the application dir. touch .reload or one of the classes:
The memory usage goes up by another 50Mb (huge amount of mem. taking
into account the fact that it used only 20Mb under any load befor).
Do this another time and another 20Mb gone etc..
The JProfiler marks the memory used by classes . And it can be
clearly seen the GC can't release most of it.
I AM sure this is not the application that takes all the memory.
Another hint : after making the server to reload application i can see
that the number of threads ON EVERY RELOAD is going up by ~10-20
threads .The # of threads goes lower over time but not the mem usage.
My system:
Sparc Solaris 9 ,Java 1.4.2_04-b05, Sun ONE Web Server 6.1SP5
Evgeny

Answer 1

my guess is that - because of '.reload' , web container tries to
recompile all the classes that you use within your web application and
hence the memory growth is spiking up.What do you mean by "tries to recompile"?The classes in
Web-inf are already compiled! And i have only ~5 jsp's .
(the most part of the applic. is a complicated business logic)
If you are talking about reloading them ,yes,that's the purpose of .reload,
isn't it? :).But it seems that container uses the memory for it's own
classes: the usage of memory for my classes don't really grow
that much (if at all) after reload (according to profiler)
Also the real problem is that the memory usage grows to much for
too long (neither seen it going down) and thus ends with OutOfMemory.
if you are seeing the memory growth to be flat in stress environment,
then I am not sure that why do you think that there is a memory leak ?There is no memory leak in stress environment.
There is memory leak while reloading the application.
It is a memory hog for sure (~20-30Mb for every reload).
Memory leak?It seems that way because i can't see memory usage go
down and after a lot of reloads OutOfMemory is thrown.
also, what is jvm heap that you use ? did you try jvm tune options like -
XX:+AggressiveHeap ?256Mb.I can set it bigger ,but how do i know that it will not just delay
the problem ?
Thanks for response.
Evgeny