Fix: UPF N3 Interface Nil While Running 10K Subscriber Load Test

[anaswarac-dac]

What type of PR is this?

/kind bug fix

What this PR does / why we need it:

During a 10K subscriber load test, a few UEs failed due to the UPF N3 interface becoming nil, which resulted in PDU Resource Setup Failure. This issue impacts large-scale subscriber load scenarios. When the UPF N3 interface becomes nil, session establishment fails, affecting network reliability and scalability. Ensuring stable N3 interface handling is critical for high-capacity deployments and load testing.

Test Report Added?:

/kind TESTED

[Copilot]

Pull Request Overview

This PR addresses a race condition during high-load scenarios (10K subscribers) where the UPF N3 interface becomes nil, causing PDU Resource Setup failures. The fix implements proper locking mechanisms to prevent concurrent access issues when reading and writing the N3Interfaces slice.

• Added mutex locking around N3Interfaces initialization and updates
• Protected N3Interfaces read access with read locks to prevent reading nil or partially initialized data

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
pfcp/handler/handler.go	Added write lock protection around N3Interfaces initialization to prevent race conditions during concurrent updates
context/ngap_build.go	Added read lock protection when accessing N3Interfaces to prevent reading nil or partially initialized interface data

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I think there are a couple issues with the Lock

[gab-arrobo]

+1