Pulsar Flaky test report 2021-11-01 for PR builds in CI

[Lari Hotari <lh...@apache.org>]

Dear Pulsar community members,

Here's a report of the flaky tests in Pulsar CI during the observation
period of 2021-10-04 - 2021-11-01 .
The full report has been also updated to a Google Sheet,
https://docs.google.com/spreadsheets/d/165FHpHjs5fHccSsmQM4beeg6brn-zfUjcrXf6xAu4yQ/edit?usp=sharing
Test method name Number of build failures due to this test
org.apache.pulsar.broker.service.ReplicatorTest.testTopicReplicatedAndProducerCreate
56
org.apache.pulsar.broker.service.ReplicatorRateLimiterTest.testReplicatorRateLimiterDynamicallyChange
50
org.apache.pulsar.broker.service.persistent.SimpleProducerConsumerTestStreamingDispatcherTest.testConcurrentConsumerReceiveWhileReconnect
48
org.apache.pulsar.broker.admin.TopicPoliciesTest.testDisableSubscribeRate 45
org.apache.pulsar.broker.admin.TopicPoliciesTest.testGetDispatchRateApplied
38
org.apache.pulsar.client.api.KeySharedSubscriptionTest.testRemoveFirstConsumer
29
org.apache.pulsar.functions.source.batch.BatchSourceExecutorTest.testLifeCycle
28
org.apache.pulsar.broker.admin.TopicPoliciesTest.testGetSetSubscribeRate 23
org.apache.pulsar.broker.admin.TopicPoliciesTest.testGetSubscribeRateApplied
22
org.apache.pulsar.broker.service.PersistentTopicE2ETest.testBrokerConnectionStats
22
org.apache.pulsar.functions.source.batch.BatchSourceExecutorTest.testPushLifeCycle
22
org.apache.pulsar.broker.stats.PrometheusMetricsTest.testCompaction 18
org.apache.pulsar.broker.service.persistent.PersistentTopicStreamingDispatcherE2ETest.testBrokerConnectionStats
18
org.apache.pulsar.metadata.LocalMemoryMetadataStoreTest.testSharedInstance
16
org.apache.pulsar.broker.service.persistent.PersistentSubscriptionMessageDispatchStreamingDispatcherThrottlingTest.testRelativeMessageRateLimitingThrottling
14
org.apache.pulsar.tests.integration.io.sources.debezium.PulsarDebeziumSourcesTest.testDebeziumMsSqlSource
12
org.apache.pulsar.io.elasticsearch.ElasticSearchClientTests.testBulkRetry 12
org.apache.pulsar.tests.integration.functions.java.PulsarFunctionsJavaProcessTest.testJavaExclamationFunction
8
org.apache.pulsar.tests.integration.transaction.TransactionTest.transferNormalTest
8
org.apache.pulsar.metadata.ZKSessionTest.testReacquireLeadershipAfterSessionLost
7
org.apache.pulsar.broker.service.ReplicatorTest.testConcurrentReplicator 7

Markdown formatted summary reports for each test class can be accessed at
https://github.com/lhotari/pulsar-flakes/tree/master/2021-10-04-to-2021-11-01
(type 't' to activate search by filename in GitHub UI, then type the test
class name to find the report)

Some of the flaky tests seen in the above report have already been fixed.
One of such test is LocalMemoryMetadataStoreTest.testSharedInstance (fixed
by https://github.com/apache/pulsar/pull/12540) . The test report doesn't
capture all test failures and there might also be some other flakiness
issues such as problems where the test environment runs out of memory. One
of such issue was recently fixed by
https://github.com/apache/pulsar/pull/12547 .

*We need more help in addressing the flaky tests. Please join the efforts
so that we can get CI to a more stable state. *

To coordinate the work,
1) please search for an existing issues or search for all flaky issues with
"flaky" or the test class name (without package) in the search:
https://github.com/apache/pulsar/issues?q=is%3Aopen+flaky+sort%3Aupdated-desc
2) If there isn't an issue for a particular flaky test failure that you'd
like to fix, please create an issue using the "Flaky test" template at
https://github.com/apache/pulsar/issues/new/choose
3) Please comment on the issue that you are working on it.

We have a few active contributors working on the flaky tests, thanks for
the contributions.

I'm looking forward to more contributors joining the efforts. Please join
the #testing channel on Slack if you'd like to ask questions and tips about
reproducing flaky tests locally and how to fix them.
Sharing stories about fixing flaky tests is also helpful for sharing the
knowledge about how flaky tests can be fixed. That's a valuable way to
contribute too.
*Some of the flaky tests might be actual real production code bugs. Fixing
the flaky test might result in fixing a real production code bug.*

*Current contributors, please keep up the good work! *
*New contributors, you are welcome to join the efforts! You will learn
about Pulsar and its internals as a side-effect. *
*If you'd love to learn Pulsar internals and Pulsar OSS development, start
by fixing flaky tests.*

BR,  -Lari