This commit addresses 7 critical issues identified during the alert system audit:
**P0 Critical - Race Conditions Fixed:**
1. **dispatchAlert race in NotifyExistingAlert** (lines 5486-5497)
- Changed from RLock to Lock to hold mutex during dispatchAlert call
- dispatchAlert calls checkFlapping which writes to maps (flappingHistory, flappingActive, suppressedUntil)
- Previous code: grabbed RLock, got alert pointer, released lock, then called dispatchAlert (RACE)
- Fixed: hold Lock through dispatchAlert call
2. **dispatchAlert race in LoadActiveAlerts startup** (lines 8216-8235)
- Startup goroutines called dispatchAlert without holding lock
- Added m.mu.Lock/Unlock around dispatchAlert call in goroutine
- Also added cancellation via escalationStop channel to prevent goroutine leaks on shutdown
3. **checkFlapping documentation** (line 738)
- Added clear comment that checkFlapping requires caller to hold m.mu
- Prevents future race conditions from improper usage
**P1 Important - Data Loss Prevention:**
4. **History save race condition** (lines 177-180 in history.go)
- Added saveMu mutex to serialize disk writes
- Previous: concurrent saves could interleave, causing newer data to be overwritten by older snapshots
- Fixed: saveMu.Lock at start of saveHistoryWithRetry ensures atomic disk writes
- Newer snapshots now always win over older ones
**P2 Memory Leak Prevention:**
5. **PMG anomaly tracker cleanup** (lines 7318-7331)
- Added cleanup for pmgAnomalyTrackers map (24 hour TTL based on LastSampleTime)
- Prevents unbounded growth from decommissioned/transient PMG instances
- Each tracker: ~1-2KB (48 samples + baselines)
6. **PMG quarantine history cleanup** (lines 7333-7354)
- Added cleanup for pmgQuarantineHistory map (7 day TTL based on last snapshot)
- Prevents memory leak for deleted PMG instances
- Removes both empty histories and very old histories
**P2 Goroutine Leak Prevention:**
7. **Startup notification goroutine cancellation** (lines 8218-8234)
- Added select with escalationStop channel to cancel startup notifications
- Prevents goroutines from continuing after Stop() is called
- Scales with number of restored critical alerts
All fixes maintain proper lock ordering and prevent deadlocks by ensuring locks are held when accessing shared maps.
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