[feat][client] PIP-234: Support shared resources in PulsarAdmin to reduce thread usage

[3pacccccc]

Main Issue: #24796

Motivation

When creating multiple PulsarAdmin clients in the same JVM, each client currently creates its own set of resources (event loops, timers, DNS resolvers). This leads to excessive thread consumption and memory usage when many admin clients are instantiated.

This change allows PulsarAdmin clients to share resources through the PulsarClientSharedResources mechanism, similar to what's already available for PulsarClient.

Modifications

1. Added sharedResources(PulsarClientSharedResources) method to PulsarAdminBuilder API
2. Modified PulsarAdminBuilderImpl to accept and propagate shared resources configuration
3. Updated PulsarAdminImpl constructor to pass shared resources to HTTP connector
4. Enhanced AsyncHttpConnector to utilize shared resources:
   • Event loop group for I/O operations
   • Netty timer for timeouts and scheduling
   • DNS resolver for name resolution
5. Added test to verify shared resources are properly reused across multiple admin clients.

Verifying this change

• Make sure that the change passes the CI checks.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

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

Matching PR in forked repository

PR in forked repository: 3pacccccc#29

[lhotari]

LGTM. Great work @3pacccccc

[Copilot]

Pull Request Overview

This PR adds support for sharing resources (event loop groups, timers, and DNS resolvers) across multiple PulsarAdmin client instances to reduce memory footprint and thread usage when creating many clients in the same JVM.

Key changes:

• Added sharedResources parameter to PulsarAdminBuilder and AsyncHttpConnector
• Updated AsyncHttpConnector to manage shared and created event loop groups
• Added new test cases to verify shared resource behavior

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
PulsarAdminBuilder.java	Added API method to accept PulsarClientSharedResources
PulsarAdminBuilderImpl.java	Implemented sharedResources method and stored shared resources field
PulsarAdminImpl.java	Updated constructors to accept and pass shared resources to connector
AsyncHttpConnectorProvider.java	Updated getConnector to accept shared resources parameter
AsyncHttpConnector.java	Added logic to handle shared resources, including managing event loops, DNS resolvers, and cleanup
PulsarAdminBuilderImplTest.java	Added test cases for shared resources functionality
AsyncHttpConnectorTest.java	Updated test constructor calls to include null shared resources parameter

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 84.78261% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.23%. Comparing base (676ba07) to head (9048d50).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...client/admin/internal/http/AsyncHttpConnector.java	82.92%	2 Missing and 5 partials ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #24893       +/-   ##
=============================================
+ Coverage     38.56%   74.23%   +35.67%     
- Complexity    13262    33877    +20615     
=============================================
  Files          1856     1913       +57     
  Lines        145287   149488     +4201     
  Branches      16877    17371      +494     
=============================================
+ Hits          56025   110973    +54948     
+ Misses        81696    29647    -52049     
- Partials       7566     8868     +1302     

Flag	Coverage Δ
inttests	26.28% <43.47%> (+0.10%)	⬆️
systests	22.70% <43.47%> (-0.06%)	⬇️
unittests	73.75% <84.78%> (+39.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
.../client/admin/internal/PulsarAdminBuilderImpl.java	76.19% <100.00%> (+43.18%)	⬆️
.../pulsar/client/admin/internal/PulsarAdminImpl.java	79.04% <100.00%> (+10.47%)	⬆️
...dmin/internal/http/AsyncHttpConnectorProvider.java	88.88% <ø> (ø)
...client/admin/internal/http/AsyncHttpConnector.java	85.08% <82.92%> (+11.72%)	⬆️

... and 1407 files with indirect coverage changes

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