It would be very useful to have a waitForMerges() method on the IndexWriter.
Right now, the only way i can see to achieve this is to call IndexWriter.close()
ideally, there would be a method on the IndexWriter to wait for merges without actually closing the index.
This would make it so that background merges (or optimize) can be waited for without closing the IndexWriter, and then reopening a new IndexWriter
the close() reopen IndexWriter method can be problematic if the close() fails as the write lock won't be released
this could then result in the following sequence:
- close() - fails
- force unlock the write lock (per close() documentation)
- new IndexWriter() (acquires write lock)
- finalize() on old IndexWriter releases the write lock
- Index is now not locked, and another IndexWriter pointing to the same directory could be opened
If you don't force unlock the write lock, opening a new IndexWriter will fail until garbage collection calls finalize() the old IndexWriter
If the waitForMerges() method is available, i would likely never need to close() the IndexWriter until right before the process being shutdown, so this issue would not occur (worst case scenario, the waitForMerges() fails)