[jira] [Resolved] (LUCENE-4711) IBM J9 1.7.0 JIT bug in CategoryPath

["Shai Erera (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-4711?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Shai Erera resolved LUCENE-4711.
--------------------------------

       Resolution: Fixed
    Fix Version/s: 5.0
                   4.2
    Lucene Fields: New,Patch Available  (was: New)

I already committed a fix, opened the bug so that it's on record.
                
> IBM J9 1.7.0 JIT bug in CategoryPath
> ------------------------------------
>
>                 Key: LUCENE-4711
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4711
>             Project: Lucene - Core
>          Issue Type: Bug
>          Components: modules/facet
>            Reporter: Shai Erera
>            Assignee: Shai Erera
>             Fix For: 4.2, 5.0
>
>
> When running facet tests with IBM J9 1.7.0, most of the tests fail with bizarre exceptions from CategoryPath (AIIOBE mostly). I tried to add few asserts to CategoryPath, but they didn't help to reveal the bug.
> Today I ran a single test {{TestAssociationExample}} (randomly picked) w/ -Dtests.iters=1000 and it failed too on the same error. If run w/ -Xint, it doesn't fail.
> In the end, Gilad and I discovered that when {{CategoryPath(String... components)}} constructor is used, which inside does {{this.components = components}}, the bug is triggered. At some point, probably after JIT kicks in, the array's length is 0'ed !!!
> We've added the following workaround to CategoryPath:
> {code}
> // TODO: revisit when IBM releases Java 7 newer than SR3 (with a fix)
> // to validate, run e.g. TestAssociationExample with -Dtests.iters=1000
> private static final boolean IS_J9_JAVA7 = Constants.JRE_IS_MINIMUM_JAVA7 && Constants.JVM_VENDOR.contains("IBM");
> ...
> public CategoryPath(final String... components) {
>   assert components.length > 0 : "use CategoryPath.EMPTY to create an empty path";
>   if (IS_J9_JAVA7) {
>     // On IBM J9 Java 1.7.0, if we do 'this.components = components', then
>     // at some point its length becomes 0 ... quite unexpectedly. If JIT is
>     // disabled, it doesn't happen. This bypasses the bug by copying the 
>     // array (note, Arrays.copyOf did not help either!).
>     this.components = new String[components.length];
>     System.arraycopy(components, 0, this.components, 0, components.length);
>   } else {
>     this.components = components;
>   }
>   length = components.length;
> }
> {code}

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