gistfile1.txt

local eventHealth = {}
local updateHealth = {}
local alreadyUpdated = {}
local units = {["player"] = true}

for i=1, 40 do
   units["raid" .. i] = true
end


if( frame ) then frame:UnregisterAllEvents(); frame:SetScript("OnUpdate", nil); frame:SetScript("OnEvent", nil); frame:Hide() end

frame = CreateFrame("Frame")
frame:RegisterEvent("UNIT_HEALTH")
frame:SetScript("OnEvent", function(self, event, unit)
      eventHealth[unit] = UnitHealth(unit)
      alreadyUpdated[unit] = nil
end)

frame:SetScript("OnUpdate", function(self, elapsed)
      for unit in pairs(units) do
         local health = UnitHealth(unit)
         if( eventHealth[unit] and updateHealth[unit] and updateHealth[unit] ~= eventHealth[unit] and not alreadyUpdated[unit] ) then
            print("Health diff for", UnitName(unit), "event:", eventHealth[unit], "update:", health)
            alreadyUpdated[unit] = true
         end
         
         updateHealth[unit] = health
      end 
      
end)