Fatal Error: Allowed Memory Size of 134217728 Bytes Exhausted (CodeIgniter + XML-RPC)
ini_set('memory_limit', '-1'); is not a proper solution. Please don't do that.
Your PHP code may have a memory leak somewhere and you are telling the server to just use all the memory that it wants. You wouldn't have fixed the problem at all. If you monitor your server, you will see that it is now probably using up most of the RAM and even swapping to disk.
You should probably try to track down the offending code in your code and fix it.
ini_set('memory_limit', '-1'); overrides the default PHP memory limit.
The correct way is to edit your
memory_limit to your desire value.
As from your question,
128M (which is the default limit) has been exceeded, so there is something seriously wrong with your code as it should not take that much.
If you know why it takes that much and you want to allow it set
memory_limit = 512M or higher and you should be good.