LantaoJin commented on code in PR #5348:
URL: https://github.com/apache/calcite/pull/5348#discussion_r4333921527
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core/src/test/java/org/apache/calcite/rel/RelCollationTest.java:
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@@ -220,6 +228,71 @@ class RelCollationTest {
assertThat(CLUSTERED.reverse(), is(CLUSTERED));
}
+ /** Test case for
+ * <a
href="https://issues.apache.org/jira/browse/CALCITE-7872";>[CALCITE-7872]
+ * RelCollations and RelCollationImpl can deadlock during class
+ * initialization</a>.
+ *
+ * <p>Tests that the deprecated constants {@code RelCollationImpl.EMPTY} and
+ * {@code RelCollationImpl.PRESERVE} are the same objects as
+ * {@link RelCollations#EMPTY} and {@link RelCollations#PRESERVE}, whichever
+ * of the two classes is initialized first. They used to be null if
+ * {@code RelCollations} was initialized first. */
+ @Test void testDeprecatedConstantsInEitherInitializationOrder()
+ throws Exception {
+ final List<Class<?>> classes =
+ Arrays.asList(RelCollations.class, RelCollationImpl.class);
+ for (List<Class<?>> order : Arrays.asList(classes,
Lists.reverse(classes))) {
+ final ClassLoader loader = new IsolatingClassLoader();
+ for (Class<?> c : order) {
+ Class.forName(c.getName(), true, loader);
+ }
+ final Class<?> relCollations =
+ loader.loadClass(RelCollations.class.getName());
+ final Class<?> relCollationImpl =
+ loader.loadClass(RelCollationImpl.class.getName());
+ for (String name : Arrays.asList("EMPTY", "PRESERVE")) {
+ final Object expected = relCollations.getField(name).get(null);
+ assertThat(expected, notNullValue());
+ assertThat(relCollationImpl.getField(name).get(null),
+ sameInstance(expected));
+ }
+ }
+ }
+
+ /** Test case for
+ * <a
href="https://issues.apache.org/jira/browse/CALCITE-7872";>[CALCITE-7872]
+ * RelCollations and RelCollationImpl can deadlock during class
+ * initialization</a>.
+ *
+ * <p>Tests that two threads can initialize {@link RelCollations} and
+ * {@link RelCollationImpl} at the same time. The static initializers of the
+ * two classes used to depend on each other, so the threads deadlocked. */
+ @Test void testConcurrentClassInitialization() throws Exception {
Review Comment:
With the fix, it is deterministic.
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