I have concurrent goroutines which want to append a (pointer to a) struct to the same slice. How do you write that in Go to make it concurrency-safe?
This would be my concurrency-unsafe code, using a wait group:
var wg sync.WaitGroup
MySlice = make([]*MyStruct)
for _, param := range params {
wg.Add(1)
go func(param string) {
defer wg.Done()
OneOfMyStructs := getMyStruct(param)
MySlice = append(MySlice, &OneOfMyStructs)
}(param)
}
wg.Wait()
I guess you would need to use go channels for concurrency-safety. Can anyone contribute with an example?
There is nothing wrong with guarding the MySlice = append(MySlice, &OneOfMyStructs)
with a sync.Mutex. But of course you can have a result channel with buffer size len(params)
all goroutines send their answers and once your work is finished you collect from this result channel.
If your params
has a fixed size:
MySlice = make([]*MyStruct, len(params))
for i, param := range params {
wg.Add(1)
go func(i int, param string) {
defer wg.Done()
OneOfMyStructs := getMyStruct(param)
MySlice[i] = &OneOfMyStructs
}(i, param)
}
As all goroutines write to different memory this isn't racy.