From: "dtuttle1@..." <dtuttle1@...>
Date: 2007-07-17T09:05:05+09:00
Subject: Re: How to reclaim memory without GC.start

On Jul 16, 4:31 pm, Travis D Warlick Jr <warli...@operissystems.com>
wrote:
> dtutt...@gmail.com wrote:
> > Hi - I have a memory and cpu-constrained embedded app. There's a long-
> > running loop with a local object (buffer) which eats up memory. A
> > GC.start on every iteration will reclaim it, but that eats the cpu.
>
> > Is there a way to deallocate the memory used by the temporary objects?
>
> > file = File.new file_path
> > while buffer = file.read(512)
> >   stream_host_connection.write buffer
> >   stream_host_connection.flush
> >   # GC.start - too expensive
> > end
>
> Someone please correct me if I'm wrong, but...
>
> You don't need to deallocate buffer every time because it is not getting
> duplicated at the beginning of every iteration -- it is being
> overwritten, so the memory usage for buffer will always stay at 512
> bytes (plus the static overhead for the object).
>
> Deallocating it every time would actually increase CPU usage because you
> would be deleting and recreating the buffer object at the beginning of
> every iteration.
>
> If you're really constrained on memory, you might want to consider
> decreasing the amount that you read at every iteration.  However,
> remember that you increase your CPU usage by the same factor that you
> decrease your memory usage in this case.
>
> --
>   Travis Warlick
>
>   "Programming in Java is like dealing with your mom --
>    it's kind, forgiving, and gently chastising.
>    Programming in C++ is like dealing with a disgruntled
>    girlfriend -- it's cold, unforgiving, and doesn't tell
>    you what you've done wrong."

The object is being overwritten, but the old copies aren't being
garbage collected. I know this because the memory does stay constant
if I call GC.start on every iteration.
I think I'll go with a c extension for this small part of the code.

Thanks, Dave