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https://issues.apache.org/jira/browse/LUCENE-2779?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12965245#action_12965245
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Uwe Schindler edited comment on LUCENE-2779 at 11/30/10 11:53 AM:
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Yonik: You are right. Sun Java 5 creates an ArrayList and then uses the
Iterator and adds each key to the ArrayList. After that it calls toArray on the
ArrayList. This is safe, as the iterator is documented to be safe. Java 6 is
safe as AbstractCollection.toArray() is oficially documented to behave
correctly.
If Shai wants to keep this code, he should at least use ArrayList instead of
HashSet for the keys, as cloning is much faster then. But as
ArrayList(Collection) uses toArray() in its ctor it may also be broken.
Maybe Shai uses IBM JRocket? Or Harmony (Harmony is currently broken,
HARMONY-6681)?
was (Author: thetaphi):
Yonik: You are right. In Sun Java 5 (src.zip, ConcurrentHashMap.java, line
1207) you can see how the toArray is implemented for KeySet. It creates an
ArrayList and then uses the Iterator and adds each key to the ArrayList. After
that it calls toArray on the ArrayList. This is safe, as the iterator is
documented to be safe.
If Shai wants to keep this code, he should at least use ArrayList instead of
HashSet for the keys, as cloning is much faster then.
Maybe Shai uses IBM JRocket? Or Harmony?
> Use ConcurrentHashMap in RAMDirectory
> -------------------------------------
>
> Key: LUCENE-2779
> URL: https://issues.apache.org/jira/browse/LUCENE-2779
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Store
> Reporter: Shai Erera
> Assignee: Shai Erera
> Priority: Minor
> Fix For: 3.1, 4.0
>
> Attachments: LUCENE-2779-backwardsfix.patch, LUCENE-2779.patch,
> LUCENE-2779.patch, LUCENE-2779.patch, TestCHM.java
>
>
> RAMDirectory synchronizes on its instance in many places to protect access to
> map of RAMFiles, in addition to updating the sizeInBytes member. In many
> places the sync is done for 'read' purposes, while only in few places we need
> 'write' access. This looks like a perfect use case for ConcurrentHashMap
> Also, syncing around sizeInBytes is unnecessary IMO, since it's an AtomicLong
> ...
> I'll post a patch shortly.
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