英文:
Go maps fails the concurency test
问题
当我运行以下代码时：
import (
"log"
"sync"
"testing"
"time"
)
func TestConcurrency(t *testing.T) {
var mutex sync.RWMutex
dictionary := make(map[interface{}]interface{})
go func() {
var value interface{}
for {
go func() {
mutex.Lock()
dictionary["Key"] = ""
mutex.Unlock()
}()
go func() {
mutex.RLock()
value = dictionary["Key"]
mutex.RUnlock()
}()
}
log.Println(value)
}()
}
使用：
go test -race fileName.go
结果是：
发现1个数据竞争
我该如何解决这个问题？
我有很多并发的写入和读取操作。
英文:
When I run the following code:
import (
"log"
"sync"
"testing"
"time"
)
func TestConcurrency(t *testing.T) {
var mutex sync.RWMutex
dictionary := make(map[interface{}]interface{})
go func() {
var value interface{}
for {
go func() {
mutex.Lock()
dictionary["Key"] = ""
mutex.Unlock()
}()
go func() {
mutex.RLock()
value = dictionary["Key"]
mutex.RUnlock()
}()
}
log.Println(value)
}()
}
using :
go test -race fileName.go
It results in:
Found 1 data race(s)
How can I solve this?
I have many concurrent writes and reads.
答案1
得分: 4
如果你查看竞争检测器报告的错误，你会发现它报告了在value = dictionary["Key"]这一行上的并发写操作，这意味着检测到的竞争是在value而不是dictionary上。
你同时访问了两个变量，dictionary和value。你不能使用读锁来保护对映射的读取和对value变量的写入。你要么需要第二个互斥锁，要么需要始终使用mutex.Lock来串行访问这两个变量。
英文:
If you look at the error presented by the race detector, you would see that it reported concurrent writes on the value = dictionary["Key"] line, meaning the race being detected is on value, not dictionary.
You are concurrently accessing 2 variables, dictionary and value. You can't use the read lock to protect reads on the map, and writes to the value variable. You either need a second mutex, or you need to always use mutex.Lock to serialize access to both variables.
答案2
得分: 0
这段代码将正常工作：
go func() {
mutex.Lock()
value = dictionary["Key"]
mutex.Unlock()
}()
它保护变量value免受并发写入的影响。
英文:
This code will work correctly:
go func() {
mutex.Lock()
value = dictionary["Key"]
mutex.Unlock()
}()
It protects the variable value from concurrent write.
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