Re: example of excessive memory use (shootout)
fft1976 wrote:
On Jun 30, 10:21 am, Andrew Thompson <andrewtho...@gmail.com> wrote:
On Jul 1, 2:40 am, fft1976 <fft1...@gmail.com> wrote:
Why is Java using 15MB here?
Is this a troll?
No. Can you explain why you think it might be? Is this a sensitive
topic?
Posting a complaint about memory usage using a microbenchmark that
probably has little bearing on real-world considerations.
I was under the impression that JVM had a fixed memory overhead per
process, and maybe a small (2-fold or so?) overhead for the data
structures.
It depends on many factors. There is the overhead of the VM itself, plus
the requisite set of Java classes (system loaders, object, arrays,
probably I/O as well, etc.).
Some other shootout entries use less than 1MB, so the fixed overhead
should be small. (The linked entry uses very few libraries, by the
way).
Do other entries start up their own interpreter? Probably not.
The data structures needed here are perhaps 0.1KB in size. So, again,
why 15MB and not 1MB or so?
Because there's a lot more going on then you've cared to try to think about.
And would the memory usage go up to 150MB if the data structures were
ten times larger?
Probably not. It depends on the data structures and how they scale with
size.
--
Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth