Need help to pick up the live objects while using ObjectSpace#each_object

Ruby
1

I wrote the code below :

class Animal
attr_reader :number

def initialize(name, number)
@name = name
@number = number
end

def self.all_numbers
ObjectSpace.each_object(self).map(&:number)
end
end

an1 = Animal.new(‘Dog’, 23)
an2 = Animal.new(‘Tiger’, 18)

Animal.all_numbers

=> [18, 23]

Somewhere I read that ObjectSpace#each_object can pick up objects that
are abandoned but not yet garbage-collected. It would be a good idea to
check the validity of that before using it in this context. My question
is - How to do that ?

2

Love U Ruby wrote in post #1131229:

I wrote the code below :…
…
Somewhere I read that ObjectSpace#each_object can pick up objects that
are abandoned but not yet garbage-collected. It would be a good idea to
check the validity of that before using it in this context. My question
is - How to do that ?

Here’s the result of a simple experiment I did. It shows that
ObjectSpace#each_object lists objects that have been deleted but not
yet garbage-collected:

include ObjectSpace

class Cat
def initialize(n)
@a = []
n.times {|i| @a << {}}
end
end

def nobjects(msg)
puts “\n#{msg}\n”

Note ObjectSpace#each_object enumerates over all

objects reported by ObjectSpace#count_objects.

puts “number of hash objects = #{ObjectSpace.count_objects[:T_HASH]}”
end

n = 10000 # Create this number of empty hashes

nobjects(“at start”)

=> at start

=> number of hash objects = 77

cat = Cat.new(n)
nobjects(“after creating an array of #{n} empty hashes”)

=> after creating an array of 10000 empty hashes

=> number of hash objects = 10044

cat = nil
sleep(5)
nobjects(“after setting cat => nil and waiting 5 secs”)

=> after setting cat => nil and waiting 5 secs

=> number of hash objects = 10045

garbage_collect
nobjects(“after forcing garbage collection”)

=> after forcing garbage collection

=> number of hash objects = 29