But, locking should be fine even for this "hammering" use case (and if it's not, that's a bug, and I'd really like to know about it!).
I have hammered over 2.5 million 5-10k docs into an index this way (a realtime system that I had not yet added a special load call to) and had 0 problems. One indexwriter of course. It's not recommended (utterly dog slow and man did Hibernate add to the loading problem until I addressed batch loading...) but it sure did work flawlessly.
