fix: handle awaitTermination result and ensure proper ExecutorService shutdown by 2897robo · Pull Request #3244 · iluwatar/java-design-patterns

2897robo · 2025-04-07T04:23:05Z

What does this PR do?

This pull request addresses a high severity issue (java:S2095) reported by SonarCloud in the App.java file of the leader-followers module.

The issue was:

"Use try-with-resources or close this 'ExecutorService' in a 'finally' clause."
(See SonarCloud rule java:S2095)

What was the problem?

The ExecutorService created using Executors.newFixedThreadPool(...) was not guaranteed to shut down properly, which could lead to:

Resource leakage
Threads not terminating gracefully
Reliability issues in long-running systems

What does this PR change?

Wrapped ExecutorService usage inside a try-finally block
Handled the return value of awaitTermination(...) to check whether the shutdown was completed within the timeout
Added a fallback shutdownNow() in the finally block
This fix is in line with the best practices for managing ExecutorService lifecycle in Java

Why not try-with-resources?

ExecutorService does not implement AutoCloseable, so it cannot be used with try-with-resources.
Hence, we use try-finally as the proper alternative here.

References

Rule: java:S2095 - Resources should be closed
SonarCloud issue: AZXOQpt67L73unJ7u3kh

✅ Fixes: #2865
🧹 Impact: Improves resource handling, stability, and SonarCloud quality gates

… shutdown - Added handling for the result of awaitTermination to avoid Sonar warning - Wrapped ExecutorService with try-finally for proper shutdown (java:S2095) - Prevents potential resource leak and aligns with best practices Fixes: iluwatar#2865 Note: ExecutorService is not AutoCloseable, so try-with-resources is not applicable. Used try-finally instead.

github-actions · 2025-04-07T04:23:18Z

PR Summary

This PR addresses a high severity issue (java:S2095) reported by SonarCloud by improving resource handling and ensuring proper ExecutorService shutdown in the App.java file. It wraps ExecutorService usage inside a try-finally block, handles awaitTermination return value, and adds a fallback shutdownNow().

Changes

File	Summary
`leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java`	The `ExecutorService` is now properly shut down using a `try-finally` block. The `awaitTermination` result is handled to check for successful shutdown within the timeout, and a fallback `shutdownNow()` is used if necessary. The logger is also defined explicitly using `LoggerFactory.getLogger(...)`.

autogenerated by presubmit.ai

github-actions

✅ LGTM!

Review Summary

Commits Considered (2)

c217d2d: Merge branch 'iluwatar:master' into master
634e77a: fix: handle awaitTermination result and ensure proper ExecutorService shutdown
Added handling for the result of awaitTermination to avoid Sonar warning
Wrapped ExecutorService with try-finally for proper shutdown (java:S2095)
Prevents potential resource leak and aligns with best practices

Fixes: #2865

Note: ExecutorService is not AutoCloseable, so try-with-resources is not applicable. Used try-finally instead.

Files Processed (1)

leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java (1 hunk)

Actionable Comments (0)

Skipped Comments (1)

leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java [80-82]

possible issue: "Unnecessary shutdownNow() call."

2897robo · 2025-04-07T04:40:09Z

Hi @iluwatar, kindly reminding for review when you get a chance 🙂
This PR fixes a SonarCloud high severity issue and passed all checks.
Thanks in advance!

iluwatar · 2025-04-07T17:58:10Z

+      addTasks(taskSet);
+      boolean terminated = exec.awaitTermination(2, TimeUnit.SECONDS);
+      if (!terminated) {
+        System.out.println("Executor did not terminate in the given time.");


Use Lombok's @slf4j annotation for logging

github-actions

✅ LGTM!

Review Summary

Commits Considered (1)

0f78c56: fix: add missing logger definition for SLF4J
Defined logger explicitly with LoggerFactory.getLogger(...)
Ensured compatibility with Lombok's @slf4j annotation
Fixed compilation error caused by missing 'log' variable

Files Processed (2)

leader-followers/pom.xml (1 hunk)
leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java (2 hunks)

Actionable Comments (0)

Skipped Comments (1)

leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java [26-36]

enhancement: "Improve logging in finally block."

github-actions

✅ LGTM!

Review Summary

Commits Considered (1)

a758249: Merge branch 'iluwatar:master' into master

Files Processed (0)

Actionable Comments (0)

Skipped Comments (0)

@slf4j

- Defined logger explicitly with LoggerFactory.getLogger(...) - Ensured compatibility with Lombok's @slf4j annotation - Fixed compilation error caused by missing 'log' variable

github-actions

✅ LGTM!

Review Summary

Commits Considered (1)

a98e1ea: fix: add missing logger definition for SLF4J
Defined logger explicitly with LoggerFactory.getLogger(...)
Ensured compatibility with Lombok's @slf4j annotation
Fixed compilation error caused by missing 'log' variable

Files Processed (2)

leader-followers/pom.xml (1 hunk)
leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java (2 hunks)

Actionable Comments (0)

Skipped Comments (1)

leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java [26-36]

enhancement: "Improve exception handling and logging in finally block."

2897robo · 2025-04-08T02:28:51Z

Hi @iluwatar, thank you for the feedback!

✅ I've addressed your review comment by defining the SLF4J logger explicitly instead of using Lombok's @Slf4j.
✅ Also confirmed the proper use of try-finally since ExecutorService is not AutoCloseable.

Let me know if there's anything else I should improve 🙌

iluwatar · 2025-04-08T17:13:36Z

+    <dependency>
+      <groupId>org.projectlombok</groupId>
+      <artifactId>lombok</artifactId>
+      <version>1.18.24</version>
+      <scope>provided</scope>
+    </dependency>


The dependency already exists in parent pom.xml, so no need to declare it here

iluwatar · 2025-04-08T17:17:17Z

- */
+@Slf4j
 public class App {
+  private static final Logger log = LoggerFactory.getLogger(App.class);


No need to declare the logger like this. After inserting the annotation you can just log like LOGGER.info("hello")

github-actions

✅ LGTM!

Review Summary

Commits Considered (1)

4ef609c: fix: add missing logger definition for SLF4J

Files Processed (1)

leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java (2 hunks)

Actionable Comments (0)

Skipped Comments (0)

sonarqubecloud · 2025-04-09T05:32:09Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
85.7% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

2897robo · 2025-04-09T05:34:33Z

✅ Updated code based on review:

Removed duplicate Lombok dependency (exists in parent POM)
Removed manual logger definition
Using Lombok's @slf4j annotation with LOGGER.warn() syntax

Let me know if there's anything else to revise.
Thanks for reviewing as always! 🙌

2897robo · 2025-04-10T05:07:05Z

Hi @iluwatar! 🙌
I’ve updated the PR based on all your feedback:

✅ Removed the redundant Lombok dependency (parent POM already includes it)
✅ Removed manual logger definition
✅ Replaced it with Lombok's @slf4j and updated to LOGGER.warn(...) style

All checks have passed ✅ and there are no conflicts with base branch.
When you have a moment, I’d really appreciate a final review or merge.
Thanks again for your time and guidance! 🙏

iluwatar · 2025-04-10T16:34:16Z

Looks good! Thank you for the contribution 🎉

@all-contributors please add @2897robo for code

allcontributors · 2025-04-10T16:34:19Z

@iluwatar

@2897robo already contributed before to code

2897robo · 2025-04-10T16:48:57Z

Thank you so much for reviewing and merging! 🙏
It was a valuable learning experience to contribute and receive feedback.
I’ll continue contributing whenever I can!

Much appreciated! 🚀

2897robo added 2 commits April 7, 2025 13:20

Merge branch 'iluwatar:master' into master

c217d2d

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2897robo force-pushed the master branch from a758249 to 0f78c56 Compare April 8, 2025 02:01

fix: add missing logger definition for SLF4J

a98e1ea

- Defined logger explicitly with LoggerFactory.getLogger(...) - Ensured compatibility with Lombok's @slf4j annotation - Fixed compilation error caused by missing 'log' variable

2897robo force-pushed the master branch from 0f78c56 to a98e1ea Compare April 8, 2025 02:12

github-actions Bot reviewed Apr 8, 2025

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iluwatar requested changes Apr 8, 2025

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fix: add missing logger definition for SLF4J

4ef609c

github-actions Bot reviewed Apr 9, 2025

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iluwatar approved these changes Apr 10, 2025

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iluwatar merged commit 6cadf25 into iluwatar:master Apr 10, 2025
2 checks passed

github-actions Bot mentioned this pull request Apr 14, 2026

Pull Request: SonarQube Security & Code Quality Fixes #3466

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2897robo commented Apr 7, 2025

What does this PR do?

What was the problem?

What does this PR change?

Why not try-with-resources?

References

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Quality Gate passed

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