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https://issues.apache.org/jira/browse/LUCENE-5573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13961741#comment-13961741
]
Dawid Weiss commented on LUCENE-5573:
-------------------------------------
Definitely doable with asmlib... and sounds like a fun side-project.
{code}
public class ClinitCycle {
public static void main(String[] args) throws Exception {
ClassReader cr = new ClassReader(X.class.getName());
ClassNode cn = new ClassNode();
cr.accept(cn, ClassReader.SKIP_DEBUG);
System.out.println("SUPER: " + cn.superName);
List methods = cn.methods;
for (int i = 0; i < methods.size(); ++i) {
MethodNode method = (MethodNode) methods.get(i);
System.out.println("Method: " + method.name);
if (method.instructions.size() > 0) {
InsnList instructions = method.instructions;
instructions.accept(new MethodVisitor(Opcodes.ASM5) {
@Override
public void visitTypeInsn(int opcode, String type) {
System.out.println(opcode + " -> " + type);
}
@Override
public void visitMethodInsn(int opcode, String owner, String name,
String desc, boolean itf) {
System.out.println(opcode + " -> " + name + " [" + desc + ", " +
owner + "]");
}
});
}
}
}
}
{code}
> Deadlock during class loading/ initialization
> ---------------------------------------------
>
> Key: LUCENE-5573
> URL: https://issues.apache.org/jira/browse/LUCENE-5573
> Project: Lucene - Core
> Issue Type: Bug
> Reporter: Dawid Weiss
> Assignee: Robert Muir
> Fix For: 4.8, 5.0
>
> Attachments: A.java, C.java, LUCENE-5573.patch, Main.java, X.java
>
>
> It's always worth looking into those randomized failures.
> http://builds.flonkings.com/job/Lucene-trunk-Linux-Java7-64-test-only/81259/console
> Log quote:
> {code}
> [junit4] 2> ==== jstack at approximately timeout time ====
> [junit4] 2> "Lucene Merge Thread #0" ID=25 RUNNABLE
> [junit4] 2> at
> org.apache.lucene.codecs.lucene45.Lucene45DocValuesProducer.getSortedSet(Lucene45DocValuesProducer.java:541)
> [junit4] 2> at
> org.apache.lucene.codecs.perfield.PerFieldDocValuesFormat$FieldsReader.getSortedSet(PerFieldDocValuesFormat.java:285)
> [junit4] 2> at
> org.apache.lucene.index.SegmentReader.getSortedSetDocValues(SegmentReader.java:500)
> [junit4] 2> at
> org.apache.lucene.index.SegmentMerger.mergeDocValues(SegmentMerger.java:204)
> [junit4] 2> at
> org.apache.lucene.index.SegmentMerger.merge(SegmentMerger.java:119)
> [junit4] 2> at
> org.apache.lucene.index.IndexWriter.mergeMiddle(IndexWriter.java:4068)
> [junit4] 2> at
> org.apache.lucene.index.IndexWriter.merge(IndexWriter.java:3664)
> [junit4] 2> at
> org.apache.lucene.index.ConcurrentMergeScheduler.doMerge(ConcurrentMergeScheduler.java:405)
> [junit4] 2> at
> org.apache.lucene.index.ConcurrentMergeScheduler$MergeThread.run(ConcurrentMergeScheduler.java:482)
> [junit4] 2>
> [junit4] 2>
> "TEST-TestLucene45DocValuesFormat.testSortedSetVariableLengthVsUninvertedField-seed#[7362FE36DE729D42]"
> ID=23 RUNNABLE
> [junit4] 2> at
> org.apache.lucene.index.SortedSetDocValues.<clinit>(SortedSetDocValues.java:72)
> [junit4] 2> at
> org.apache.lucene.index.DocTermOrds.iterator(DocTermOrds.java:767)
> [junit4] 2> at
> org.apache.lucene.search.FieldCacheImpl.getDocTermOrds(FieldCacheImpl.java:1214)
> [junit4] 2> at
> org.apache.lucene.index.BaseDocValuesFormatTestCase.doTestSortedSetVsUninvertedField(BaseDocValuesFormatTestCase.java:2342)
> [junit4] 2> at
> org.apache.lucene.index.BaseDocValuesFormatTestCase.testSortedSetVariableLengthVsUninvertedField(BaseDocValuesFormatTestCase.java:2375)
> [junit4] 2> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native
> Method)
> [junit4] 2> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
> [junit4] 2> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> [junit4] 2> at java.lang.reflect.Method.invoke(Method.java:606)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1617)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:826)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:862)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:876)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:50)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleFieldCacheSanity$1.evaluate(TestRuleFieldCacheSanity.java:51)
> [junit4] 2> at
> org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:46)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.rules.SystemPropertiesInvariantRule$1.evaluate(SystemPropertiesInvariantRule.java:55)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:49)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:70)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:48)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:359)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:783)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:443)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:835)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.RandomizedRunner$3.evaluate(RandomizedRunner.java:737)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.RandomizedRunner$4.evaluate(RandomizedRunner.java:771)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:782)
> [junit4] 2> at
> org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:46)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:42)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.rules.SystemPropertiesInvariantRule$1.evaluate(SystemPropertiesInvariantRule.java:55)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:39)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:39)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:43)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:48)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:70)
> [junit4] 2> at
> org.apache.lucene.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:55)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
> [junit4] 2> at
> com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:359)
> {code}
> Robert looked into it and was wtf'd, quote:
> {code}
> what happened here...
> {code}
> I looked into it and was wtf'd, quote (from my head):
> {code}
> wtf?!
> {code}
> I looked deeper at the code and it's a beautiful and classic class loading
> deadlock. I don't think I've seen an example of this in real life *ever*,
> except for this one case.
> Problem description.
> 1. Thread A attempts to return a new instance of RandomAccessOrds:
> {code}
> return new RandomAccessOrds() {
> {code}
> RandomAccessOrds extends SortedSetDocValues and has a final static field
> which in turn loads RandomAccessOrds (circular reference).
> 2. Thread B attempts to create:
> {code}
> private class Iterator extends SortedSetDocValues {
> {code}
> 3. If thread B starts loading SortedSetDocValues, it blocks other threads
> from doing so. If, at the same time, thread A starts loading RandomAccessOrds
> then thread A will eventually attempt to initialize SortedSetDocValues and
> both will wait for each other indefinitely.
> I attach a simpler example that does the same as a POC.
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