Memory exhaustion

[Fred Wan]

Hi, I'm encountering a problem which may not have to do with swarm directly
but which I find worrying all the same. Maybe someone has encountered the
same problem and/or can give me some advice. In the program I include, a
number of agents (TargetBugs) are put in a grid (Grid2dImpl) and a list. The
agents are removed at each step when they move across the grid according to
some probability. After a number of steps (50), ModelSwarm creates new ones
and this process continues indefinitely. The size of the virtual machine
(jdk) almost always grows continuously, indicating memory exhaustion. With
some VMs (Kaffe under NT4 and the Visual Cafe's VM) this does _not_ happen
and memory is returned to the system. Because swarm uses its own way of
memory allocation, java's finalize() method can't be used to check what
happens. I'm wondering if and how can be checked whether memory is being
held somewhere where it shouldn't, or if it is just this is due to different
garbage collection procedures of the VMs. It is also troublesome that when
increasingly large amounts of memory are claimed by the VM, the whole
execution slows down (and less importantly, so do the rest of the tasks on
the system).

Thanks,
Fred Wan,
Vrije Universiteit Amsterdam,
The Netherlands.

SimpleBug.scm
Description: application/icq-scm

TargetBug.java
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StartSimpleBug.java
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ObserverSwarm.java
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ModelSwarm.java
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FoodSpace.java
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Agent.java
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Makefile
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