# fatal error: concurrent map read and map write

- **ID:** `go/panic-concurrent-map-read-write`
- **Domain:** go
- **Category:** runtime_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

One goroutine reads a map while another writes to it without synchronization.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 1.0+ | active | — | — |

## Workarounds

1. **** (95% success)
   ```
   mu.RLock()
v := m[k]
mu.RUnlock()
   ```
2. **** (90% success)
   ```
   var m sync.Map
if v, ok := m.Load(k); ok { _ = v }
   ```

## Dead Ends

- **** — Copy itself races with the writer; the fatal error still fires during copy. (85% fail)
- **** — Go does not serialize concurrent map access; runtime deliberately aborts. (95% fail)