[CALCITE-2521] RelMetadataTest#testMetadataHandlerCacheLimit takes 8-20 seconds and it looks useless

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.17.0
• Fix Version/s: 1.18.0
• Component/s: core
• Assignee: Julian Hyde
• Reporter: Vladimir Sitnikov
• Created: 01/Sep/18 00:27
• Updated: 23/Dec/18 00:12
• Resolved: 05/Sep/18 19:50

Description

org.apache.calcite.test.RelMetadataTest#testMetadataHandlerCacheLimit was introduced in CALCITE-1808

Travis takes 17 seconds to execute RelMetadataTest

[INFO] Running org.apache.calcite.test.RelMetadataTest
[WARNING] Tests run: 140, Failures: 0, Errors: 0, Skipped: 6, Time elapsed: 17.318 s - in 

  /** Test case for
   * <a href="https://issues.apache.org/jira/browse/CALCITE-1808">[CALCITE-1808]
   * JaninoRelMetadataProvider loading cache might cause
   * OutOfMemoryError</a>. */
  @Test public void testMetadataHandlerCacheLimit() {
    Assume.assumeTrue("If cache size is too large, this test may fail and the "
            + "test won't be to blame",
        SaffronProperties.INSTANCE.metadataHandlerCacheMaximumSize().get()
            < 10_000);
    final int iterationCount = 2_000;
    final RelNode rel = convertSql("select * from emp");
    final RelMetadataProvider metadataProvider =
        rel.getCluster().getMetadataProvider();
    final RelOptPlanner planner = rel.getCluster().getPlanner();
    for (int i = 0; i < iterationCount; i++) {
      RelMetadataQuery.THREAD_PROVIDERS.set(
          JaninoRelMetadataProvider.of(
              new CachingRelMetadataProvider(metadataProvider, planner)));
      final RelMetadataQuery mq = RelMetadataQuery.instance();
      final Double result = mq.getRowCount(rel);
      assertThat(result, within(14d, 0.1d));
    }
  }

In fact, it creates 1000 metadata providers, and it does take noticeable time (e.g. 8 seconds on my notebook).

I suggest to remove the test as it spends noticeable time, and it never reproduces "out of memory".

Technically speaking the test tries to validate if org.apache.calcite.rel.metadata.JaninoRelMetadataProvider cache is bounded, however there's no assertions.

Alternative option would be to significantly increase the number of iterations, and disable the test by default