Development: Prevent race condition when accessing build agent map

[laurenzfb]

Checklist

General

• I tested all changes and their related features with all corresponding user types on a test server.
• Language: I followed the guidelines for inclusive, diversity-sensitive, and appreciative language.
• I chose a title conforming to the naming conventions for pull requests.

Server

• Important: I implemented the changes with a very good performance and prevented too many (unnecessary) database calls.
• I strictly followed the server coding and design guidelines.

Changes affecting Programming Exercises

• High priority: I tested all changes and their related features with all corresponding user types on a test server configured with the integrated lifecycle setup (LocalVC and LocalCI).

Motivation and Context

While observing the Local CI I observed an error causing an issue in the build job management:

The initial exception that was caused by a concurrent access to a Hazelcast map and thrown in the thenAccept method of the CompletableFuture for the build job result.

To handle normal build results and exceptions that have been thrown during the build job execution, we use thenAccept and exceptionally methods respectively. thenAccept gets called when everything went fine, exceptionally when something went wrong during the build job execution. Both methods are chained and thus an exception thrown in the thenAcceptmethod can trigger the execution of the exceptionally method which is not desired.

Description

• added a lock to prevent concurrent access to the Hazelcast map which should prevent the exception to be thrown
• the exception gets caught just in case
• thethenAccept and exceptionally methods get separated instead of chaining them

Steps for Testing

Test on TS3 or TS6

There isn't really a great way to test this, as the initial error rarely happened. You can test whether the exception handling for exceptions during the build job execution still works.

Prerequisites:

• 1 Admin
• 1 Programming Exercise

1. Create submission for the programming exercise
2. You should get an expected result
3. Create multiple submissions (click the submit button a few times)
4. Go to the Build Queue (Server Administration > Build Queue) and cancel the running build jobs
5. Go to the Build Agent (Server Administration > Build Agent)
6. The recently finished build jobs should reflect the cancellations

Testserver States

Note

These badges show the state of the test servers.
Green = Currently available, Red = Currently locked

Review Progress

Performance Review

• I (as a reviewer) confirm that the server changes (in particular related to database calls) are implemented with a very good performance

Code Review

• Code Review 1
• Code Review 2

Manual Tests

• Test 1
• Test 2

Summary by CodeRabbit

• New Features
  • Improved the build agent information update process with enhanced locking mechanisms.
  • Enabled asynchronous processing of build jobs for more efficient operations.

[coderabbitai]

Walkthrough

The recent update enhances the SharedQueueProcessingService by improving the handling of build agent information and the processing of build jobs. It introduces a mechanism to lock and unlock the buildAgentInformation map during updates, ensuring thread safety. Furthermore, the processBuild method now processes build jobs asynchronously by employing future results, optimizing the system's overall performance and efficiency in handling concurrent build tasks.

Changes

File Path	Change Summary
.../localci/buildagent/SharedQueueProcessingService.java	Updated the updateLocalBuildAgentInformation method to include locking and unlocking of the buildAgentInformation map. Modified the processBuild method to use future results for asynchronous build job processing.

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[reschandreas]

code lgtm

[rstief]

code looks good 👍

[egekurt123]

Manually tested on ts3, works as expected

[mateusmm01]

Demonstrated in testing session. Code also lgtm

[Strohgelaender]

lgtm