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https://issues.apache.org/jira/browse/LUCENENET-181?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12700688#action_12700688
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Eyal Post commented on LUCENENET-181:
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{quote}
One term-cache per thread is what is intended in Java (or I think so).
{quote}
No It's not. Here are the reasons:
1. If that's what they intended then they would have made enumerators static.
2. There can be many instances of TermInfosReader in a process each needing a
*different* termEnum. It's doesn't make sense for them to use the same enum
instance becuase an enum should be created *per TermInfosReader*.
{quote}
As I wanted to show in "TestCase", if you make "enumerators" static, cache is
created only once per thread, otherwise it is created with every new instance
of TermInfosReader
{quote}
Which is exactly how it should work.
{quote}
( A private field would be enough for that type of cache).
{quote}
A private field would *not* be enough becuase multiple threads using the same
TermInfosReader will get the same enumerator each stepping on the other's toe.
That is exactly what ThreadLocal is preventing.
> Port of ThreadLocal is wrong?
> -----------------------------
>
> Key: LUCENENET-181
> URL: https://issues.apache.org/jira/browse/LUCENENET-181
> Project: Lucene.Net
> Issue Type: Improvement
> Reporter: Digy
> Priority: Minor
> Attachments: TestCase.cs
>
>
> AFAIK, "ThreadLocal" in Java is there to hold objects which are intented to
> be used thread-wide. So, its port-equivalent "LocalDataStoreSlot" should
> contain objects related with the executing thread. But, since they are not
> declared as "static" in Analyzer.cs, FieldsReader.cs, SegmentReader.cs and
> TermInfosReader.cs, they are created with every class contruction, changing
> the behaviour of "ThreadLocal" and possibly resulting in performance
> degradation.
> I will attach a test case for this issue.
> If I am wrong, then there is no problem. But If I am right we are in trouble;
> Since adding "static" to variables declared as LocalDataStoreSlot results in
> failing of almost all test cases.
> DIGY
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