From: Kent Dahl <kentda@...>
Date: 2002-05-25T06:56:42+09:00
Subject: Re: FAQ for newcomers familiar with lower level language

Kyle Rawlins wrote:
> In short, though memory management is made very easy in Ruby and other GC'd
> languages, it worries me greatly that it could be considered good programming
> practice to write anything beyond a simple script without thinking about issues
> of resource usage.

I concur. I haven't noticed any memory usage profilers for Ruby and I
think this is a weakness. 

I scrapped my plans of writing a simple personal accounting tool in Ruby
with FLTK for my PDA because the style of programming I had gotten used
to with Ruby, turned out to chew up too much memory for the poor little
thing. 

Are there existing/planned hooks into the GC? I know I'd like to be able
to get some feedback from the GC about what the peaks are, how much it
has freed since some point etc. Basically like those thermometers that
measure daily bottom and daily top, plus status I could diff at
(arbitrary) points in my code.

GC.reset_max_mem_usage
# create insanely many objects
puts GC.max_mem_usage #=> writes the maximum memory usage 
		      #   that has occured since reset_max_mem_usage

prestatus = GC.mem_status
# do create (and release) insanely many objects
poststatus = GC.mem_status
diff = poststatus - prestatus
puts diff.total_allocated #=> total number of allocated bytes in period
puts diff.total_released  #=> total number of bytes free'd during GC in
the period

I'm just thinking out loud in code here, and seriously braindamaged by
the way I used to write (naive) speed tests myself in other languages.

If nothing else, I would like to see a requireable .so module that could
allow this kind of thing for debugging. (No, I'm not writing one. gc.c
was very scary last time I looked inside it. :-)

-- 
(\[ Kent Dahl ]/)_    _~_    __[ http://www.stud.ntnu.no/~kentda/ ]___/~
 ))\_student_/((  \__d L b__/  NTNU - graduate engineering - 4. year  )
( \__\_�|�_/__/ ) _)Industrial economics and technological management(
 \____/_�_\____/ (____engineering.discipline_=_Computer::Technology___)