LongFieldMapperTests.testFetchMany intermittent test failure

[jordan-powers]

CI Link

https://gradle-enterprise.elastic.co/s/rmoxu3efbdjuy

Repro line

./gradlew ":server:test" --tests "org.elasticsearch.index.mapper.LongFieldMapperTests.testFetchMany" -Dtests.seed=317E4C1CCBB3354D -Dtests.locale=mni-IN -Dtests.timezone=Europe/Istanbul -Druntime.java=24

Does it reproduce?

Yes

Applicable branches

main

Failure history

No response

Failure excerpt

java.lang.AssertionError: fetching [8.113364145238966E18, 4.203550126536837E18, 7634906914949243073]
Expected: iterable with items [<4203550126536837120L>, <7634906914949243073L>, <8113364145238966000L>] in any order
    but: not matched: <4203550126536837000L>

[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)

[jordan-powers]

This was an intermittent failure out of randomized testing, but I was able to write a test that consistently reproduces the issue:

public void testFetchLargeDouble() throws IOException {
    assertFetch(randomFetchTestMapper(), "field", ((Long) 4203550126536837120L).doubleValue(), randomFetchTestFormat());
}

[Kubik42]

This happens because 4203550126536837120L is too large for double to successfully represent without loosing precision. Test results demonstrate this:

  2> REPRODUCE WITH: ./gradlew ":server:test" --tests "org.elasticsearch.index.mapper.LongFieldMapperTests.testFetchLargeDouble" -Dtests.seed=317E4C1CCBB3354D -Dtests.locale=mni-IN -Dtests.timezone=Europe/Istanbul -Druntime.java=24
  2> java.lang.AssertionError: fetching 4.203550126536837E18
    Expected: iterable with items [<4203550126536837120L>] in any order
         but: not matched: <4203550126536837000L>
        at __randomizedtesting.SeedInfo.seed([317E4C1CCBB3354D:7E0C5B9C3135D8F2]:0)
        at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:20)
        at org.elasticsearch.test.ESTestCase.assertThat(ESTestCase.java:2710)
        at org.elasticsearch.index.mapper.MapperTestCase.lambda$assertFetch$47(MapperTestCase.java:899)
        at org.elasticsearch.index.mapper.MapperServiceTestCase.withLuceneIndex(MapperServiceTestCase.java:362)
        at org.elasticsearch.index.mapper.MapperTestCase.assertFetch(MapperTestCase.java:869)
        at org.elasticsearch.index.mapper.LongFieldMapperTests.testFetchLargeDouble(LongFieldMapperTests.java:57)

4203550126536837120L -> 4203550126536837000L. When converting to double, we get 4.203550126536837E18 (last 3 digits are lost).

We could use BigDecimal here or perhaps this is just a test problem.

[Kubik42]

This is a test issue. Here we declare the type of every value as long, despite alternating between long and double.

[Kubik42]

The problem is here. This code generates a list of values, which may alternate between double and long, meanwhile this just hard codes the field type to long. Replacing "long" with "double" makes this test pass.