[Tests] Reduce flakiness of BacklogQuotaManagerTest

[lhotari]

Motivation

BacklogQuotaManagerTest is flaky.

one example:

Error:  Tests run: 21, Failures: 1, Errors: 0, Skipped: 4, Time elapsed: 280.77 s <<< FAILURE! - in org.apache.pulsar.broker.service.BacklogQuotaManagerTest
Error:  testTriggerBacklogQuotaSizeWithReader(org.apache.pulsar.broker.service.BacklogQuotaManagerTest)  Time elapsed: 4.371 s  <<< FAILURE!
java.lang.AssertionError: expected [1] but found [0]
	at org.testng.Assert.fail(Assert.java:99)
	at org.testng.Assert.failNotEquals(Assert.java:1037)
	at org.testng.Assert.assertEqualsImpl(Assert.java:140)
	at org.testng.Assert.assertEquals(Assert.java:122)
	at org.testng.Assert.assertEquals(Assert.java:907)
	at org.testng.Assert.assertEquals(Assert.java:917)
	at org.apache.pulsar.broker.service.BacklogQuotaManagerTest.testTriggerBacklogQuotaSizeWithReader(BacklogQuotaManagerTest.java:255)
	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 org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:132)
	at org.testng.internal.InvokeMethodRunnable.runOne(InvokeMethodRunnable.java:45)
	at org.testng.internal.InvokeMethodRunnable.call(InvokeMethodRunnable.java:73)
	at org.testng.internal.InvokeMethodRunnable.call(InvokeMethodRunnable.java:11)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

this happeneded in https://github.com/apache/pulsar/pull/10566/checks?check_run_id=2573662149#step:10:1928

Several test methods are flaky. Locally testConsumerBacklogEvictionWithAckTimeQuota was very flaky and that issue was also fixed.

Modifications

• use Awaitility for checking PersistentTopicInternalStats in a few test methods
• disable batching in all producers
• cleanup test by using the TIME_TO_CHECK_BACKLOG_QUOTA constant
• speed up test by reducing TIME_TO_CHECK_BACKLOG_QUOTA from 5 seconds to 3 seconds
• fix race condition in testConsumerBacklogEvictionWithAckTimeQuota which was causing flakiness
  • resolve the race by pausing for 1 second after acknowledging 10 messages for the 1. consumer. This makes the ledgers to expire at different times so that the last ledger with 4 messages will expire later than others.

[eolivelli]

LGTM

[eolivelli]

it looks like that the test you wanted to fix failed on CI

https://github.com/apache/pulsar/pull/10572/checks?check_run_id=2575259667

[lhotari]

it looks like that the test you wanted to fix failed on CI

@eolivelli Thanks for pointing that out. I made some more changes in the PR to address flakiness. In particular, there was a challenge with the backlog size which seems to be off by one in some cases. I added some comments in the changes about it. PTAL