Shai Erera created LUCENE-4711:
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Summary: 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
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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