arenaが思ったとおりに動作しているか確認するためのコード。 2013/12/27時点でcloneしたmrubyでは正常動作しなかったが、#1637のプルリクで1/3に直っている。 この例だとarenaに保護されているようだが、いつ放置されるのかよくわかっていない。

arenaoverflow.c

//! make arenaoverflow.bin

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
#include <mruby.h>
#include <mruby/compile.h>
#include <mruby/value.h>

mrb_value create( mrb_state *mrb, mrb_value factory )
{
    return mrb_funcall( mrb, factory, "create", 0 );
}

void mrb_state_print( mrb_state *mrb )
{
    printf( "----------------\n"
            "mrb_state stats\n"
            "\n"
            "%20s = %10d\n"
            "%20s = %10d\n",
            "mrb->arena_idx", mrb->arena_idx,
            "mrb->arena_capa", mrb->arena_capa
        );
}

int main( void )
{
    mrb_state *mrb = mrb_open();

    /* load class */
    FILE *fp = fopen( "factory.rb", "r" );
    if ( fp == NULL ) {
        perror( "fopen" );
        exit( 1 );
    }
    mrb_load_file( mrb, fp );

    /* factory: FactoryTest class */
    mrb_value factory =
        mrb_obj_value( mrb_class_get( mrb, "FactoryTest" ) );

    /* (a) people is alloced on heap region */
    mrb_value *people = mrb_malloc( mrb, sizeof(mrb_value)*1E6 );
    /* /\* (b) people is alloced on stack *\/ */
    /* mrb_value people[1000000]; */

    mrb_state_print( mrb );

    printf( "---------------\n" );
    printf( "person create\n" );
    for ( int i = 0; i < 1E6; i++ ) {
        /* (1) method call on another func */
        people[i] = create( mrb, factory );
        /* /\* (2) method call on toplevel *\/ */
        /* people[i] = mrb_funcall( mrb, factory, "create", 0 ); */
    }

    mrb_state_print( mrb );

    printf( "---------------\n" );
    printf( "person no\n" );
    /* some errors will occur if gc collect the object */
    for ( int i = 0; i < 1E6; i++ ) {
        mrb_funcall( mrb, people[i], "no", 0 );
    }

    mrb_state_print( mrb );

    mrb_close( mrb );
    return 0;
}

factory.rb

class Person
  @@total = 0
  def initialize
#     p "person.new no#{@@total}"
    @n = @@total
    @@total += 1
  end
  def no
#     p "#{@n}"
  end
end

class FactoryTest
  def initialize
    p "Factory Test"
  end
  def self.create
    Person.new
  end
end

makefile

MRUBYPATH := /home/amiq/.opt/src/mruby

CFLAGS += -I$(MRUBYPATH)/include
LDFLAGS += -L$(MRUBYPATH)/build/host/lib -lmruby -lm

CFLAGS += -std=gnu99 -O0 -g

all: arenaoverflow.bin

%.bin: %.c
	$(CC) -o $@ $< $(CFLAGS) $(LDFLAGS)

.PHONY: clean
clean:
	rm -f *.bin *.o

.PHONY: check-syntax
check-syntax:
	$(CC) $(CHK_SOURCES) $(CFLAGS) $(LDFLAGS) -fsyntax-only