I have a mobile application that is suffering from slow-down over time. My hunch, (In part fed by this article,) is that this is due to fragmentation of memory slowing the app down, but I’m not sure. Here’s a pretty graph of the app’s memory use over time:
fraggle rock http://kupio.com/image-dump/fragmented.png
The 4 peaks on the graph are 4 executions of the exact same task on the app. I start the task, it allocates a bunch of memory, it sits for a bit (The flat line on top) and then I stop the task. At that point it calls System.gc(); and the memory gets cleaned up.
As can be seen, each of the 4 runs of the exact same task take longer to execute. The low-points in the graph all return to the same level so there do not seem to be any memory leaks between task runs.
What I want to know is, is memory fragmentation a feasible explanation or should I look elsewhere first, bearing in mind that I’ve already done a lot of looking? The low-points on the graph are relatively low so my assumption is that in this state the memory would not be very fragmented since there can’t be a lot of small memory holes to be causing problems.
I don’t know how the j2me memory allocator works though, so I really don’t know. Can anyone advise? Has anyone else had problems with this and recognises the memory profile of the app?
If you’ve got a little bit of time, you could test your theory by re-using the memory by using Memory Pool techniques: each run of the task uses the ‘same’ chunks of memory by getting them from the pool and returning them at release time.
If you’re still seeing the degrading performance after doing this investigation, it’s not memory fragmentation causing the problem. Let us all know your results and we can help troubleshoot further.