Out-of-Memory Handling in Long-Running / Server Applications

Hi,

My application has highly variable running times and memory demands
based on the problems submitted to it. Some hard-to-solve (or
insoluble) problems will run it out of memory.

When memory is exhausted in the inner loop of the program (the only
place it's going to happen), I catch the OutOfMemoryError, release the
storage, trigger a GC (forcing it would seem desirable, but I'm not
sure how to do that) and report the failure back up the call chain.
The vast majority of the RAM is used in the search tree, which is
linked only upwardly from the leaves and the leaves are all in a
priority queue, so relinquishing the priority queue is enough to make
all the objects in the tree unreferenceable.

This technique sometimes works and sometimes does not. I.e., when it
doesn't work the program gets another OOM very shortly after or during
the my OOM handling and dies.

Until recently, this application was mostly run from the command line so
this behavior was not such a big problem. Now it's being used much more
in its Web-App form (running in Tomcat 5.5, at the moment), this
inadequate handling is becoming a problem.


What techniques are available for handling OOM errors in situations
where simply dying on the spot is not an option?


Thanks.

Randall Schulz

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