ayende/ravendb — pull request #487 by steinho (2013-11-22 09:59:39+00:00)
Title: ItemsToDelete is not threadsafe - fixing this via lock to avoid potentia...

Get the following error on production system - might be the source for the other problem fixed in previous pull request

The code in singlestepreduce starts background threads all using the same ItemsToDelete List, so this fix will make it thread safe.

An alternative would be to use var itemsToDelete = new ConcurrentSet