[CI] CancellableRateLimitedFluxIteratorTests testCancellation failing

[thecoop]

Similar previous error: #87112

Build scan:
https://gradle-enterprise.elastic.co/s/rzfy4vf6ajniq/tests/:plugins:repository-azure:test/org.elasticsearch.repositories.azure.CancellableRateLimitedFluxIteratorTests/testCancellation

Reproduction line:

./gradlew ':plugins:repository-azure:test' --tests "org.elasticsearch.repositories.azure.CancellableRateLimitedFluxIteratorTests.testCancellation" -Dtests.seed=23C67FEEB19CBD6A -Dtests.locale=ko -Dtests.timezone=Pacific/Rarotonga -Druntime.java=18

Applicable branches:
main 7.17

Reproduces locally?:
Didn't try

Failure history:
Failure dashboard for org.elasticsearch.repositories.azure.CancellableRateLimitedFluxIteratorTests#testCancellation

Failure excerpt:

java.lang.AssertionError: 
Expected: <[3, 4]>
     but: was <[4]>

  at __randomizedtesting.SeedInfo.seed([23C67FEEB19CBD6A:F5F120982F238AEC]:0)
  at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:18)
  at org.junit.Assert.assertThat(Assert.java:956)
  at org.junit.Assert.assertThat(Assert.java:923)
  at org.elasticsearch.repositories.azure.CancellableRateLimitedFluxIteratorTests.lambda$testCancellation$7(CancellableRateLimitedFluxIteratorTests.java:197)
  at org.elasticsearch.test.ESTestCase.assertBusy(ESTestCase.java:1143)
  at org.elasticsearch.test.ESTestCase.assertBusy(ESTestCase.java:1116)
  at org.elasticsearch.repositories.azure.CancellableRateLimitedFluxIteratorTests.testCancellation(CancellableRateLimitedFluxIteratorTests.java:197)
  at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
  at java.lang.reflect.Method.invoke(Method.java:577)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:49)
  at org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:45)
  at org.apache.lucene.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:48)
  at org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:64)
  at org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:843)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:490)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:45)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:41)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:47)
  at org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:64)
  at org.apache.lucene.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:54)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:850)
  at java.lang.Thread.run(Thread.java:833)

[elasticsearchmachine]

Pinging @elastic/es-distributed (Team:Distributed)

[pxsalehi]

This is not main. It's 7.17. Removing the blocker label since based on the previous failure and fix, doesn't seem like a block. Maybe @fcofdez can confirm?

[idegtiarenko]

Discussed with @fcofdez, this could be reproduced with:

Subject: [PATCH] format
---
Index: modules/repository-azure/src/main/java/org/elasticsearch/repositories/azure/CancellableRateLimitedFluxIterator.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/modules/repository-azure/src/main/java/org/elasticsearch/repositories/azure/CancellableRateLimitedFluxIterator.java b/modules/repository-azure/src/main/java/org/elasticsearch/repositories/azure/CancellableRateLimitedFluxIterator.java
--- a/modules/repository-azure/src/main/java/org/elasticsearch/repositories/azure/CancellableRateLimitedFluxIterator.java	(revision 943b2eae70e7395ddd6b4a8c4ef36972082ab018)
+++ b/modules/repository-azure/src/main/java/org/elasticsearch/repositories/azure/CancellableRateLimitedFluxIterator.java	(date 1704803388473)
@@ -154,6 +154,11 @@
             return;
         }
 
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
         if (queue.offer(element) == false) {
             // If the source doesn't respect backpressure, we might lose elements,
             // in that case we cancel the subscription and mark this consumer as failed
@@ -167,6 +172,11 @@
     public void cancel() {
         cancelSubscription();
         clearQueue();
+        try {
+            Thread.sleep(100);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
         done = true;
         // cancel should be called from the consumer
         // thread, but to avoid potential deadlocks

and affects both 7.17 and main