go runtime_error ai_generated true

panic: sync: WaitGroup 在上一次 Wait 返回前被复用

panic: sync: WaitGroup is reused before previous Wait has returned

ID: go/waitgroup-add-after-wait

其他格式: JSON · Markdown 中文 · English

80%修复率

89%置信度

0证据数

2024-03-22首次发现

版本兼容性

版本	状态	引入	弃用	备注
1.0+	active	—	—	—

根因分析

wg.Add() 与 wg.Wait() 并发调用。WaitGroup 约定要求所有增加计数器的 Add 调用必须先于观察到它们的 Wait。

English

wg.Add() is called concurrently with wg.Wait(). The WaitGroup contract requires all Add calls that increment the counter to happen-before the Wait that observes them.

generic

解决方案

97% 成功率

var wg sync.WaitGroup
for _, item := range items {
    wg.Add(1)
    go func(it Item) {
        defer wg.Done()
        process(it)
    }(item)
}
wg.Wait()

96% 成功率

g, ctx := errgroup.WithContext(context.Background())
for _, item := range items {
    item := item
    g.Go(func() error { return process(ctx, item) })
}
if err := g.Wait(); err != nil { return err }

无效尝试

常见但无效的做法:

80% 失败
The goroutine may start after Wait() already returned, so the counter never increments in time; still racy.
95% 失败
Timing-based synchronization is nondeterministic and fails under load or on fast machines.