How to chunk an array in Ruby

In Ruby 1.8.6, I have an array of, say, 100,000 user ids, each of which is an int. I want to perform a block of code on these user ids but I want to do it in chunks. For example, I want to process them 100 at a time. How can I easily achieve this as simply as possible?

I could do something like the following, but probably there's an easier way:

a = Array.new
userids.each { |userid|
a << userid
if a.length == 100
# Process chunk
a = Array.new
end
}
unless a.empty?
# Process chunk
end

Use [`each_slice`][1]:

require 'enumerator' # only needed in ruby 1.8.6 and before
userids.each_slice(100) do |a|
# do something with a
end

[1]:

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Rails has [`in_groups_of`][1], which under the hood uses `each_slice`.

userids.in_groups_of(100){|group|
//process group
}


[1]:

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