From: Jeff Mitchell <quixoticsycophant@...>
Date: 2004-06-10T08:42:48+09:00
Subject: spikes in memory usage


The following is an example of some memory problems I've been having
with my extension classes.  This is on AthlonXP 1.5GHz Linux with
gcc 3.3.2.

require './myclass'
size = ARGV.shift.to_i
loop {
   MyClass.new(size)
   1000.times {
      MyClass.new(size)
   }
}

size      mem usage
-------------------
1           1.6 meg
10          1.6 meg
100         2.1 meg
1000        7.8 meg
10000      61.0 meg
100000    277.0 meg
1000000    15.0 meg
10000000    2.7 meg
100000000   1.6 meg


extconf.rb
-----------
require 'mkmf'
create_makefile('myclass')


myclass.c
----------
#include "ruby.h"

struct MyStruct
{
    char* stuff ;
} ;

void myclass_free(struct MyStruct* data)
{
    free(data->stuff) ;
    free(data) ;
}

VALUE rb_myclass_initialize( VALUE self, VALUE size )
{
    struct MyStruct* data;
    Data_Get_Struct(self, struct MyStruct, data) ;
    data->stuff = (char*)malloc(NUM2LONG(size)*sizeof(char)) ;
    return self ;
}

static VALUE rb_myclass_s_allocate(VALUE klass)
{
    struct MyStruct* data ;
    VALUE obj = Data_Make_Struct(klass,
                                 struct MyStruct,
                                 0,
                                 myclass_free,
                                 data) ;
    return obj ;
}

VALUE cMyClass ;

void Init_myclass()
{
    cMyClass = rb_define_class("MyClass", rb_cObject) ;
    rb_define_alloc_func(cMyClass, rb_myclass_s_allocate) ;
    rb_define_method(cMyClass, "initialize", rb_myclass_initialize, 1) ;
}



	
		
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