我讀了這個，這個和這個，但沒有一個能解決我的問題..我正在嘗試異步讀取 2 個文件，所以我寫了以下內(nèi)容：//readlines.gopackage mainimport ( "bufio" "os")// readLines reads a whole file into memory// and returns a slice of its lines.func readLines(path string) ([]string, error) { file, err := os.Open(path) if err != nil { return nil, err } defer file.Close() var lines []string scanner := bufio.NewScanner(file) for scanner.Scan() { lines = append(lines, scanner.Text()) } return lines, scanner.Err()}并將其稱為：package mainimport ( "fmt" "os" "github.com/gocarina/gocsv")func (s *stocks) Read() { fmt.Println("Reading") stockFile, err := os.OpenFile("current_invenory.csv", os.O_RDWR|os.O_CREATE, os.ModePerm) if err != nil { panic(err) } defer stockFile.Close() stocks := []systemStock{} if err := gocsv.UnmarshalFile(stockFile, &stocks); err != nil { // Load stocks from file panic(err) } *s = stocks}package mainimport ( "fmt" "os" "github.com/gocarina/gocsv")func (t *transactions) Read() { fmt.Println("Reading") trxFile, err := os.OpenFile("current_transactions.csv", os.O_RDWR|os.O_CREATE, os.ModePerm) if err != nil { panic(err) } defer trxFile.Close() trx := []systemTransactions{} if err := gocsv.UnmarshalFile(trxFile, &trx); err != nil { // Load stocks from file panic(err) } *t = trx}以上工作非常好： stock := stocks{} trx := transactions{} stock.Read() trx.Read() for _, s := range stock { fmt.Println("Hello", s.Code) }但是fatal error: all goroutines are asleep - deadlock!當我嘗試將它們讀取為時給出錯誤： cs, ct := readData() for _, s := range cs { fmt.Println("Hello", s.Code) } for _, t := range ct { fmt.Println("Hello trx of ", t.Code) }所以這個錯誤與我在最后一個塊中犯的錯誤（或不明白）有關(guān)~
1 回答
森欄
TA貢獻1810條經(jīng)驗 獲得超5個贊
為了同時運行這些Read方法，這些方法需要有一種在它們完成執(zhí)行時發(fā)出信號的方式。這可以通過多種方式完成，但這里有兩種需要對代碼進行最少修改的方式。stockstransactions
解決方案 1
使用sync.WaitGroup包。使用這個包，Read方法在執(zhí)行完成后應(yīng)該執(zhí)行wg.Done()語句。它應(yīng)該看起來像這樣：
func (s *stocks) Read(wg *sync.WaitGroup) {
defer wg.Done()
fmt.Println("Reading")
stockFile, err := os.OpenFile("current_invenory.csv", os.O_RDWR|os.O_CREATE, os.ModePerm)
if err != nil {
panic(err)
}
defer stockFile.Close()
stocks := []systemStock{}
if err := gocsv.UnmarshalFile(stockFile, &stocks); err != nil { // Load stocks from file
panic(err)
}
*s = stocks
}
func (t *transactions) Read(wg *sync.WaitGroup) {
defer wg.Done()
fmt.Println("Reading")
trxFile, err := os.OpenFile("current_transactions.csv", os.O_RDWR|os.O_CREATE, os.ModePerm)
if err != nil {
panic(err)
}
defer trxFile.Close()
trx := []systemTransactions{}
if err := gocsv.UnmarshalFile(trxFile, &trx); err != nil { // Load stocks from file
panic(err)
}
*t = trx
}
func readData() (stocks, transactions) {
var wg sync.WaitGroup
wg.Add(2)
stock := stocks{}
trx := transactions{}
go stock.Read(&wg)
go trx.Read(&wg)
wg.Wait()
return stock, trx
}
解決方案 2
這種方法使用golang.org/x/sync/errgroup包。在這種情況下，您不需要自己處理同步和信令，但是使用errgroup.Go方法添加的函數(shù)需要具有嚴格的func() error簽名。您的代碼應(yīng)如下所示：
func (s *stocks) Read() error {
fmt.Println("Reading")
stockFile, err := os.OpenFile("current_invenory.csv", os.O_RDWR|os.O_CREATE, os.ModePerm)
if err != nil {
return err
}
defer stockFile.Close()
stocks := []systemStock{}
if err := gocsv.UnmarshalFile(stockFile, &stocks); err != nil { // Load stocks from file
return err
}
*s = stocks
return nil
}
func (t *transactions) Read() error {
fmt.Println("Reading")
trxFile, err := os.OpenFile("current_transactions.csv", os.O_RDWR|os.O_CREATE, os.ModePerm)
if err != nil {
return err
}
defer trxFile.Close()
trx := []systemTransactions{}
if err := gocsv.UnmarshalFile(trxFile, &trx); err != nil { // Load stocks from file
return err
}
*t = trx
return nil
}
func readData() (stocks, transactions) {
g, _ := errgroup.WithContext(context.Background())
stock := stocks{}
trx := transactions{}
g.Go(stock.Read)
g.Go(trx.Read)
if err:= g.Wait(); err != nil {
panic(err)
}
return stock, trx
}
解決方案 3
當您開始從每個 CSV 讀取時，您（正確地）將 1 添加到等待組，使等待組的內(nèi)部計數(shù)器變?yōu)?2，但是 wg.Wait() 將等到該計數(shù)器下降到零并且您沒有任何調(diào)用 wg.Done() 來做到這一點。我建議將 go stock.Read() 更改為：
go func() {
defer wg Done()
stock.Read()
}()
因此，完整的工作代碼是：
func readData() (stocks, transactions) {
var wg sync.WaitGroup
stock := stocks{}
trx := transactions{}
wg.Add(1)
go func() {
defer wg.Done()
stock.Read()
}()
wg.Add(1)
go func() {
defer wg.Done()
trx.Read()
}()
wg.Wait()
return stock, trx
}
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