[LUCENE-2097] In NRT mode, and CFS enabled, IndexWriter incorrectly ties up disk space

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.9, 2.9.1, 3.0
• Fix Version/s: 3.1, 4.0-ALPHA
• Component/s: core/index
• Lucene Fields: New
• Assignee: Michael McCandless
• Reporter: Michael McCandless
• Created: 29/Nov/09 11:06
• Updated: 28/Aug/22 12:15
• Resolved: 10/Mar/11 18:25

Description

Spinoff of java-user thread titled "searching while optimize"...

If IndexWriter is in NRT mode (you've called getReader() at least
once), and CFS is enabled, then internally the writer pools readers.
However, after a merge completes, it opens the reader against het
non-CFS segment files, and pools that. It then builds the CFS file,
as well, thus tying up the storage for that segment twice.

Functionally the bug is harmless (it's only a disk space issue).
Also, when the segment is merged, the disk space is released again
(though the newly merged segment will also be double-tied-up).

Simple workaround is to use non-CFS mode, or, don't use getReader.