Thursday, October 13, 2011

Demystified

I discovered why the total amount of memory used does not seem approximately constant across the different heap sizes. I had forgotten to take into account that a garbage collection cycle can be run for reasons other than reclaiming storage. In particular, it can be run as part of a compaction phase that precedes dumping a binary object or moving an object out of the collected heap into “pure” storage. These are not particularly interesting operations; they contribute little to the total resource usage or total time. They just cause an overestimate of the amount of storage used in very large heaps. I could correct for this, but I'm far more interested in what happens on the other end of the curve when you have a relatively small heap. More to come.
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