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t1478: fix(pulse-wrapper): add flock-based lock guard to prevent concurrent instances#4454

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alex-solovyev merged 1 commit intomainfrom
bugfix/pulse-lock-guard
Mar 13, 2026
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t1478: fix(pulse-wrapper): add flock-based lock guard to prevent concurrent instances#4454
alex-solovyev merged 1 commit intomainfrom
bugfix/pulse-lock-guard

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@alex-solovyev alex-solovyev commented Mar 13, 2026 •
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Summary

Fixes concurrent pulse supervisor instances running simultaneously.

  • Adds flock-based lock guard in pulse-wrapper.sh to prevent multiple concurrent executions
  • Addresses the pattern where 3 pulse instances were found running concurrently

Closes #4452

Summary by CodeRabbit

  • Improvements
    • Strengthened instance locking mechanism to prevent concurrent execution conflicts and ensure stable operation during simultaneous instance launches.

@alex-solovyev
fix(pulse-wrapper): add flock-based lock guard to prevent concurrent …
899d73c 
…instances (GH#4409)

14 concurrent pulse instances ran simultaneously, each spawning workers
before the previous pulse could assess running workers, resulting in 52
active workers against a 24-slot pool.

Root cause: check_dedup() uses a PID file with a TOCTOU race window —
between reading the PID file and writing the new PID, another instance
can pass the same check.

Fix: Add flock(1) -n (non-blocking) as the primary instance lock in
main(), acquired before any other check. flock is atomic at the kernel
level — no race window. The lock auto-releases on process exit
(including crashes, OOM kills, SIGKILL). Falls back gracefully to
PID-based dedup on systems without flock (e.g., macOS).
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@github-actions github-actions bot added the bug Auto-created from TODO.md tag label Mar 13, 2026
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coderabbitai bot commented Mar 13, 2026 •
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Review failed

Pull request was closed or merged during review

Walkthrough

The change introduces a robust flock-based instance locking mechanism to .agents/scripts/pulse-wrapper.sh to prevent multiple concurrent supervisor instances. A new acquire_instance_lock() function and LOCKFILE constant enforce exclusive execution early in the main flow, with fallback to PID-based dedup if flock is unavailable.

Changes

Cohort / File(s) Summary
Instance Locking Enhancement
.agents/scripts/pulse-wrapper.sh		 Added LOCKFILE constant and acquire_instance_lock() function implementing flock-based exclusive locking on FD 9. Lock acquisition enforced early in main execution path with exit on failure. PID-based dedup maintained as fallback when flock unavailable. Lifecycle documentation updated to reflect new locking guard.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

Poem

🔒 One pulse at a time shall reign supreme,
No more duplicate instances haunt the dream,
Flock guards the gate with atomic delight,
Concurrent chaos banished to night! ⚡

🚥 Pre-merge checks | ✅ 5
✅ Passed checks (5 passed)
Check name Status Explanation
Description Check ✅ Passed Check skipped - CodeRabbit’s high-level summary is enabled.
Title check ✅ Passed The title accurately summarizes the main change: adding a flock-based lock guard to pulse-wrapper.sh to prevent concurrent instances, which directly addresses the linked issue #4452.
Linked Issues check ✅ Passed The PR implements the primary fix from #4452: adding a flock-based lock in pulse-wrapper.sh to prevent concurrent pulse supervisor instances, with fallback PID-based dedup for systems without flock support.
Out of Scope Changes check ✅ Passed All changes are scoped to implementing the flock-based locking mechanism in pulse-wrapper.sh; no unrelated modifications to other components or features are present.
Docstring Coverage ✅ Passed Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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github-actions bot commented Mar 13, 2026

🔍 Code Quality Report

�[0;35m[MONITOR]�[0m Code Review Monitoring Report

�[0;34m[INFO]�[0m Latest Quality Status:
SonarCloud: 0 bugs, 0 vulnerabilities, 414 code smells

�[0;34m[INFO]�[0m Recent monitoring activity:
Fri Mar 13 18:13:32 UTC 2026: Code review monitoring started
Fri Mar 13 18:13:32 UTC 2026: SonarCloud - Bugs: 0, Vulnerabilities: 0, Code Smells: 414

📈 Current Quality Metrics

  • BUGS: 0
  • CODE SMELLS: 414
  • VULNERABILITIES: 0

Generated on: Fri Mar 13 18:13:35 UTC 2026

Generated by AI DevOps Framework Code Review Monitoring

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sonarqubecloud bot commented Mar 13, 2026

Quality Gate Passed Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarQube Cloud

@marcusquinn marcusquinn mentioned this pull request Mar 13, 2026
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@alex-solovyev alex-solovyev merged commit 8fcdb41 into main Mar 13, 2026
25 of 26 checks passed
@alex-solovyev alex-solovyev deleted the bugfix/pulse-lock-guard branch March 13, 2026 18:20
@github-actions github-actions bot mentioned this pull request Mar 13, 2026
Closed
github-actions bot pushed a commit that referenced this pull request Mar 13, 2026
@actions-user
chore: mark t1478 complete (pr:#4454 completed:2026-03-13) [skip ci]
3d93703
@marcusquinn marcusquinn added the review-feedback-scanned Merged PR already scanned for quality feedback label Mar 13, 2026
@alex-solovyev alex-solovyev mentioned this pull request Mar 13, 2026
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t1478: fix: pulse multiple supervisor instances running simultaneously

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