go runtime_error ai_generated true

fatal error: concurrent map writes

ID: go/goroutine-map-concurrent-write

Also available as: JSON · Markdown · 中文
80%Fix Rate
89%Confidence
0Evidence
2024-11-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.21 active — — —
1.22 active — — —

Root Cause

Multiple goroutines write to a Go map without synchronization, causing a runtime crash.

generic

中文

多个协程在没有同步的情况下写入Go map，导致运行时崩溃。

Workarounds

  1. 98% success Use sync.Mutex to protect all map access 
    var mu sync.Mutex
m := make(map[string]int)
// write
mu.Lock()
m["key"] = 1
mu.Unlock()
// read
mu.Lock()
val := m["key"]
mu.Unlock()
  2. 90% success Use sync.Map for concurrent-safe map operations 
    var m sync.Map
m.Store("key", 1)
val, ok := m.Load("key")

Dead Ends

Common approaches that don't work:

  1. Using a mutex only for writes but not reads 80% fail

    Concurrent reads during writes can also cause race conditions.

  2. Using a sync.Map incorrectly 65% fail

    sync.Map has specific use cases; misuse can still cause races.