Export memory usage

[stefandoorn]

My custom order export currently simply exports all orders to either CSV or Excel. On the first run in production (without grid filters) trying to export to CSV, I'm running into memory issues already with a memory limit of around 130mb:

Symfony\Component\Debug\Exception\OutOfMemoryException: Error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 20480 bytes)
  File "vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php", line 2780
    $this->originalEntityData[$oid][$field] = $pColl;

Probably the grid filters are going to help, but memory consumption is an issue anyway probably.

[enesaktay]

might be fixed with #120 ?

[stefandoorn]

Not sure until we use generators. I think there is still the ability to load too much data in a single export (when not queuing & using grid filters).