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  • https://help.interfaceware.com/v6/how-to-troubleshoot-iguana-memory-leak

  • Find the channel leaking memory then do a code review

  • You can use the checkMemory.lua script developed by Paul Le to find a channel leaking memory over time.

    • The client would need to add this module in the shared folder, add a require statement in their main.lua, and call checkMemory() in the main function.

    • All of their channels need this script and the client needs to run the channels as normal to simulate the traffic when the memory leak occurred

    • An error should show in the Iguana logs for the leaking channel

    • If no leak is found, try decreasing the variable memoryBuffer (This is the case if the leak is small)

      Code Block
      -- Keep track of last memory usage and how many times memory has increased
memoryUsage = {
   ['lastMemoryUsage'] = 0,
   ['increasedMemoryCount'] = 0
}

isTriggered = false

local memoryLeakThreshold = 20 -- How many times memory increases to trigger an alert
local memoryBuffer        = 10 -- Buffer for what is inconsidered a memory increase

-- Useful information on how Lua handles memory: 
--   https://www.lua.org/pil/17.html

function checkMemory()

   -- Trigger garbage collection to clear unreferenced memory
   collectgarbage('collect')

   -- Get referenced memory usage
   local memoryUsageCount = collectgarbage('count')
   iguana.logDebug('Total memory in use by Lua (in Kbytes): ' .. memoryUsageCount)

   -- Check if the memory is increasing even after garbage is collected
   if memoryUsageCount - memoryBuffer > memoryUsage.lastMemoryUsage then
      iguana.logDebug('Memory in use by Lua increased (in Kbytes) by: ' .. memoryUsageCount - memoryUsage.lastMemoryUsage)
      iguana.logDebug('Total memory in use by Lua (in Kbytes): ' .. memoryUsageCount)
      -- Increase count for increasing memory usage
      memoryUsage.increasedMemoryCount = memoryUsage.increasedMemoryCount + 1
      -- Set last memory usage to the current memory usage count
      memoryUsage.lastMemoryUsage = memoryUsageCount
   elseif  memoryUsageCount < memoryUsage.lastMemoryUsage then
      -- Reset memory increase count if memory decreases
      memoryUsage.increasedMemoryCount = 0
   end

   -- If memory is increasing consistently then flag potential memory leak
   if memoryUsage.increasedMemoryCount > memoryLeakThreshold and not isTriggered then 
      iguana.logError('There may be a memory leak!')
      iguana.logError('Total memory in use by Lua (in Kbytes): ' .. memoryUsageCount)
      isTriggered = true
   end

end

Case Studies

  • Sometimes, external programs will make it look like Iguana is leaking memory.

    • 35814 - They had a monitoring program outside of Iguana that uses the Log API. It queried all the logs on an Iguana server, which cause memory to not get released properly. They now only query the last 12 hours.

    • 32422