David Turner created LUCENE-9138:
------------------------------------
Summary: Behaviour of concurrent calls to IndexInput#clone is
unclear
Key: LUCENE-9138
URL: https://issues.apache.org/jira/browse/LUCENE-9138
Project: Lucene - Core
Issue Type: Improvement
Components: core/store
Affects Versions: 8.4
Reporter: David Turner
I think this is a documentation issue, rather than anything actually wrong, but
need expert guidance to propose a fix.
The Javadocs for {{IndexInput#clone}} warn that it is not thread safe:
* <p>This method is NOT thread safe, so if the current \{@code IndexInput}
* is being used by one thread while \{@code clone} is called by another,
* disaster could strike.
*/
@Override
public IndexInput clone() {
However, there are places where {{clone()}} may be called concurrently. For
instance I believe {{SegmentReader#getFieldsReader}} clones an {{IndexInput}}
and requires no extra synchronization. I think this comment is supposed to mean
that you should not {{clone()}} an {{IndexInput}} while you're _reading or
seeking from it_ concurrently, but the precise guarantees aren't totally clear.
Furthermore there's no mention of the threadsafety of {{slice()}}. and there
seem to be similar concurrent usages of it in e.g.
{{Lucene80DocValuesProducer}}. Does this have the same guarantees as
{{clone()}}?
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org
For additional commands, e-mail: issues-h...@lucene.apache.org
