[improve][broker] Replace ScheduledExecutorService to ExecutorService in ModularLoadManagerImpl

[AnonHxy]

Motivation

An minor improvement by replacing ScheduledExecutorService to ExecutorService in ModularLoadManagerImpl

Modifications

Replace ScheduledExecutorService to ExecutorService in ModularLoadManagerImpl

• doc
• doc-required
• doc-not-needed
• doc-complete

Verifying this change

• Make sure that the change passes the CI checks.

Matching PR in forked repository

AnonHxy#30

[github-actions]

@AnonHxy Please add the following content to your PR description and select a checkbox:

- [ ] `doc` <!-- Your PR contains doc changes -->
- [ ] `doc-required` <!-- Your PR changes impact docs and you will update later -->
- [x] `doc-not-needed` <!-- Your PR changes do not impact docs -->
- [ ] `doc-complete` <!-- Docs have been already added -->

[315157973]

/pulsarbot run-failure-checks

[heesung-sohn]

@AnonHxy

The PR is causing a test failure.

 Check failure on line 785 in pulsar-broker/src/test/java/org/apache/pulsar/broker/namespace/NamespaceServiceTest.java

GitHub Actions
/ Flaky tests suite
NamespaceServiceTest.testModularLoadManagerRemoveBundleAndLoad
Cannot locate field scheduler on class org.apache.pulsar.broker.loadbalance.impl.ModularLoadManagerImpl

#17487 (comment)

[AnonHxy]

@AnonHxy

The PR is causing a test failure.

Thanks for your reminder. Fix it in this PR #19710 . PTAL

[lhotari]

Why was this cherry-picked to branch-2.11? The tests are broken in branch-2.11

  Error:  Tests run: 42, Failures: 1, Errors: 0, Skipped: 36, Time elapsed: 21.939 s <<< FAILURE! - in org.apache.pulsar.broker.namespace.NamespaceServiceTest
  Error:  testModularLoadManagerRemoveBundleAndLoad(org.apache.pulsar.broker.namespace.NamespaceServiceTest)  Time elapsed: 2.615 s  <<< FAILURE!
  org.powermock.reflect.exceptions.FieldNotFoundException: No instance field named "scheduler" could be found in the class hierarchy of org.apache.pulsar.broker.loadbalance.impl.ModularLoadManagerImpl.
  	at org.powermock.reflect.internal.matcherstrategies.FieldNameMatcherStrategy.notFound(FieldNameMatcherStrategy.java:40)
  	at org.powermock.reflect.internal.WhiteboxImpl.findSingleFieldUsingStrategy(WhiteboxImpl.java:502)
  	at org.powermock.reflect.internal.WhiteboxImpl.findFieldInHierarchy(WhiteboxImpl.java:455)
  	at org.powermock.reflect.internal.WhiteboxImpl.findFieldInHierarchy(WhiteboxImpl.java:443)
  	at org.powermock.reflect.internal.WhiteboxImpl.getInternalState(WhiteboxImpl.java:427)
  	at org.powermock.reflect.Whitebox.getInternalState(Whitebox.java:292)
  	at org.apache.pulsar.broker.namespace.NamespaceServiceTest.waitResourceDataUpdateToZK(NamespaceServiceTest.java:830)
  	at org.apache.pulsar.broker.namespace.NamespaceServiceTest.testModularLoadManagerRemoveBundleAndLoad(NamespaceServiceTest.java:789)
  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
  	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
  	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.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
  	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
  	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
  	at java.base/java.lang.Thread.run(Thread.java:840)

[lhotari]

Nevermind, cherry-picking and backporting #19710 to fix the issue in branch-2.11.