FastAPI 0.115 Async Routing & Pydantic v2: Sub-Millisecond p99 Tail Latency Tuning: Critical Incident Post-Mortem & Triage

// FastAPI 0.115 Async Routing & Pydantic v2 Production Concurrency Control Pattern
// Topic: Sub-Millisecond p99 Tail Latency Tuning: Critical Incident Post-Mortem & Triage

async function processResourceWithLease(resourceId, leaseTimeoutMs = 5000) {
  const leaseToken = crypto.randomUUID();
  const acquired = await distributedCoordination.tryAcquire(resourceId, leaseToken, leaseTimeoutMs);
  if (!acquired) {
    throw new ConcurrencyLockError(`Resource ${resourceId} is leased by a competing worker.`);
  }
  try {
    return await executeAtomicMutation(resourceId);
  } finally {
    await distributedCoordination.release(resourceId, leaseToken);
  }
}