[CI] org.elasticsearch.discovery.DiscoveryDisruptionIT#testElectMasterWithLatestVersion failures

[jimczi]

org.elasticsearch.discovery.DiscoveryDisruptionIT#testElectMasterWithLatestVersion started to fail on 6x and master recently:
https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+master+intake/1315/console
https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+6.x+intake/1034/console

The test fails with the following error (cannot reproduce locally):

java.lang.AssertionError: node [node_t1] still has [{node_t2}{H4ka7FkMQWmsZMQ3_VN1gQ}{7zSO3xGvSqGmBJqDGJynjw}{127.0.0.1}{127.0.0.1:36399}] as master expected null, but was:<{node_t2}{H4ka7FkMQWmsZMQ3_VN1gQ}{7zSO3xGvSqGmBJqDGJynjw}{127.0.0.1}{127.0.0.1:36399}>
	at __randomizedtesting.SeedInfo.seed([BB146F5E215F29E0:5BAC000A598C5A6A]:0)
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.failNotNull(Assert.java:755)
	at org.junit.Assert.assertNull(Assert.java:737)
	at org.elasticsearch.discovery.AbstractDisruptionTestCase.lambda$assertNoMaster$0(AbstractDisruptionTestCase.java:154)
	at org.elasticsearch.test.ESTestCase.assertBusy(ESTestCase.java:848)
	at org.elasticsearch.discovery.AbstractDisruptionTestCase.assertNoMaster(AbstractDisruptionTestCase.java:151)
	at org.elasticsearch.discovery.MasterDisruptionIT.testVerifyApiBlocksDuringPartition(MasterDisruptionIT.java:411)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1750)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:938)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:974)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:988)
	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:368)
	at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:817)
	at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:468)
	at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:947)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:832)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:883)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:894)
	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 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:368)
	at java.lang.Thread.run(Thread.java:748)
	Suppressed: java.lang.AssertionError: node [node_t1] still has [{node_t2}{H4ka7FkMQWmsZMQ3_VN1gQ}{7zSO3xGvSqGmBJqDGJynjw}{127.0.0.1}{127.0.0.1:36399}] as master expected null, but was:<{node_t2}{H4ka7FkMQWmsZMQ3_VN1gQ}{7zSO3xGvSqGmBJqDGJynjw}{127.0.0.1}{127.0.0.1:36399}>
		at org.junit.Assert.fail(Assert.java:88)
		at org.junit.Assert.failNotNull(Assert.java:755)
		at org.junit.Assert.assertNull(Assert.java:737)
		at org.elasticsearch.discovery.AbstractDisruptionTestCase.lambda$assertNoMaster$0(AbstractDisruptionTestCase.java:154)
		at org.elasticsearch.test.ESTestCase.assertBusy(ESTestCase.java:836)

[elasticmachine]

Pinging @elastic/es-distributed

[andrershov]

The caption mentions DiscoveryDisruptionIT#testElectMasterWithLatestVersion, but exception provided in description relates to a different test MasterDisruptionIT.testVerifyApiBlocksDuringPartition.
There is already an issue for MasterDisruptionIT #37276.
Moreover, build links no longer work.
DiscoveryDisruptionIT#testElectMasterWithLatestVersion actually was failing several times according to Kibana, and the latest failure (with logs still available) https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+master+release-tests/362/consoleFull.
From these logs, I can see that test failed when asserting no master on node_t2, which previously was a master, after introducing network disruption (second time).
And the reason for the failure seems a stall on node_t2, here the logs from this node:

1> [2019-01-21T06:27:50,301][DEBUG][o.e.c.s.MasterService    ] [node_t2] processing [node-left[{node_t0}{g7ZxqRehSF6MkXW0XJMwqg}{xasWEDc2SXiHXTigXFKYnA}{127.0.0.1}{127.0.0.1:46373} disconnected]]: execute
1> [2019-01-21T06:27:50,301][DEBUG][o.e.c.r.a.AllocationService] [node_t2] [test][0] failing shard [test][0], node[g7ZxqRehSF6MkXW0XJMwqg], [P], s[STARTED], a[id=-sTvScv4SzyovUuISa2DsQ] with unassigned info ([reason=NODE_LEFT], at[2019-01-21T11:27:50.301Z], delayed=true, details[node_left[g7ZxqRehSF6MkXW0XJMwqg]], allocation_status[no_attempt])

16 seconds stall

1> [2019-01-21T06:28:06,712][DEBUG][o.e.c.r.a.a.BalancedShardsAllocator] [node_t2] skipping rebalance due to in-flight shard/store fetches
1> [2019-01-21T06:28:06,712][TRACE][o.e.c.s.MasterService    ] [node_t2] cluster state updated, source [node-left[{node_t0}{g7ZxqRehSF6MkXW0XJMwqg}{xasWEDc2SXiHXTigXFKYnA}{127.0.0.1}{127.0.0.1:46373} disconnected]]
1> cluster uuid: Hc9PTwFsRcm09xct1FfCJg
1> version: 9

Since this test failure was failing during unstable infrastructure window period, I think we need to unmute this method.

[ywelsch]

For the reasons that @andrershov has outline above, and no recent failures of this test (testElectMasterWithLatestVersion), I'm closing this issue