Concurrency
Detect and fix race conditions and deadlocks. Fires thousands of concurrent requests to prove thread-unsafety, then applies the minimal synchronization primitive needed.From its SKILL.md
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SKILL.md
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Execute all four phases in order.
Phase 1 — Chaos Script
Write a test that fires ≥1,000 concurrent async requests or threads at the target function simultaneously. The test must assert the final state deterministically (e.g. if a counter is incremented 1,000 times, assert counter === 1000).
Phase 2 — Failure Verification
Run the test. If it passes consistently:
- Increase concurrency to 10,000.
- Add
sleep()calls mid-execution to force thread context switching.
Prove the function is unsafe before fixing it. Do not add synchronization to code that has not been shown to fail.
Phase 3 — Synchronization
Implement the minimal synchronization primitive needed (prefer in this order):
- Atomic operations (e.g.
Atomics.add,atomic.AddInt64,std::atomic) - Mutex / Lock with the smallest possible critical section
- Semaphore only if mutual exclusion alone is insufficient
Do not hold a lock across any I/O operation.
Phase 4 — Report
Re-run the test with 10,000 concurrent requests. Report the pass/fail counts.
| Metric | Before | After |
|---|---|---|
| Failures at 1k concurrent | N | 0 |
| Failures at 10k concurrent | N | 0 |
The target is 0 failures.
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