[LUCENE-2135] IndexReader.close should forcefully evict entries from FieldCache

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.9.3, 3.0.2, 3.1, 4.0-ALPHA
• Component/s: core/index
• Lucene Fields: New
• Assignee: Michael McCandless
• Reporter: Michael McCandless
• Created: 08/Dec/09 10:43
• Updated: 18/Jun/10 08:03
• Resolved: 02/Jun/10 09:37

Description

Spinoff of java-user thread "heap memory issues when sorting by a string field".

We rely on WeakHashMap to hold our FieldCache, keyed by reader. But this lacks immediacy on releasing the reference, after a reader is closed.

WeakHashMap can't free the key until the reader is no longer referenced by the app. And, apparently, WeakHashMap has a further impl detail that requires invoking one of its methods for it to notice that a key has just become only weakly reachable.

To fix this, I think on IR.close we should evict entries from the FieldCache, as long as the sub-readers are truly closed (refCount dropped to 0).

Issue Links

• is related to: LUCENE-2133 [PATCH] IndexCache: Refactoring of FieldCache, FieldComparator, SortField