sprd.rb

#file_path = some excelx file with 6 sheets.....

## WITH DUP

roo = Roo::Spreadsheet.open file_path
jobs = Concurrent::Array.new

roo.each_with_pagename do |name, sheet|
  local_sheet = sheet.dup

  jobs << Concurrent.future {
    local_sheet.last_row
  }
end

puts Concurrent.zip(*jobs).value

# 25
# 22
# 22
# 22
# 22
# 5228

## WITHOUT DUP (DOESNT WORK)

roo = Roo::Spreadsheet.open file_path
jobs = Concurrent::Array.new

roo.each_with_pagename do |name, sheet|
  local_sheet = sheet.dup

  jobs << Concurrent.future {
    local_sheet.last_row
  }
end

puts Concurrent.zip(*jobs).value

# 25
# 5228
# 5228
# 5228
# 5228
# 5228


### ALTERNATE METHOD by calling a method (works)

def get_sheet(s,n)
  s.default_sheet=n
  s
end

spreadsheet = Roo::Spreadsheet.open file_path
jobs = Concurrent::Array.new

roo.sheets.each do |sheet_name|
  jobs << Concurrent.future {
    get_sheet(spreadsheet, sheet_name).last_row
  }
end

puts Concurrent.zip(*jobs).value