Facing error ("Failed to create batch", "Java Heap Space") while loading a large number of attachments (over 30,000)

I am trying to load a large number of attachments 10,000+ and am facing errors like "Java Heap space" and "Failed to create batch", I have performed the following actions already

1) Increased Java heap space, 2) Reduce Batch size to 1.

Please let me know if you have any alternative/effecient way to get this done