如何在 Golang API 中避免内存泄漏?

01 架构

阶段1: 使用定制的 http.Client

func main() {
 keepAliveTimeout:= 600 * time.Second
 timeout:= 2 * time.Second
 defaultTransport := &http.Transport{
 Dial: (&net.Dialer{
 KeepAlive: keepAliveTimeout,}
 ).Dial,
 MaxIdleConns: 100,
 MaxIdleConnsPerHost: 100,}client:= &http.Client{
 Transport: defaultTransport,
 Timeout: timeout,
 }
}复制代码

func Func()error {
 req, err:= http.NewRequest("GET","http://example.com?q=one",nil)
 if err != nil {
 return err
 }
 resp, err:= client.Do(req)
 //=================================================
 // CLOSE THE RESPONSE BODY
 //=================================================
 if resp != nil {
 defer resp.Body.Close() // MUST CLOSED THIS
 }
 if err != nil {
 return err
 }
 //=================================================
 // READ THE BODY EVEN THE DATA IS NOT IMPORTANT
 // THIS MUST TO DO, TO AVOID MEMORY LEAK WHEN REUSING HTTP
 // CONNECTION
 //=================================================
 _, err = io.Copy(ioutil.Discard, resp.Body) // WE READ THE BODY
 if err != nil {
 return err
 }
}复制代码

type sampleChannel struct {
 Data *Sample
 Err error
}
func (u *usecase) GetSample(id int64, someparam string, anotherParam string) ([]*Sample, error) {
 chanSample := make(chan sampleChannel, 3)
 wg := sync.WaitGroup{}
 wg.Add(1)
 go func() {
 defer wg.Done()
 chanSample <- u.getDataFromGoogle(id, anotherParam) // just example of function
 }()
 wg.Add(1)
 go func() {
 defer wg.Done()
 chanSample <- u.getDataFromFacebook(id, anotherParam)
 }()
 wg.Add(1)
 go func() {
 defer wg.Done()
 chanSample <- u.getDataFromTwitter(id, anotherParam)
 }()
 wg.Wait()
 close(chanSample)
 result := make([]*Sample, 0)
 for sampleItem := range chanSample {
 if sampleItem.Error != nil {
 logrus.Error(sampleItem.Err)
 }
 if sampleItem.Data == nil {
 continue
 }
 result = append(result, sampleItem.Data)
 }
 return result
}复制代码

func (u *usecase) GetSample(id int64, someparam string, anotherParam string) ([]*Sample, error) {
 chanSample := make(chan sampleChannel, 3)
 defer close(chanSample)
 go func() {
 chanSample <- u.getDataFromGoogle(id, anotherParam) // just example of function
 }()
 go func() {
 chanSample <- u.getDataFromFacebook(id, anotherParam)
 }()
 
 go func() {
 chanSample <- u.getDataFromTwitter(id,anotherParam)
 }()
 
 result := make([]*feed.Feed, 0)
 timeout := time.After(time.Second * 2)
 for loop := 0; loop < 3; loop++ {
 select {
 case sampleItem := <-chanSample:
 if sampleItem.Err != nil {
 logrus.Error(sampleItem.Err)
 continue
 }
 if feedItem.Data == nil {
 continue
 }
 result = append(result,sampleItem.Data)
 case <-timeout:
 err := fmt.Errorf("Timeout to get sample id: %d. ", id)
 result = make([]*sample, 0)
 return result, err
 }
 }
 return result, nil;
}复制代码

func (u *usecase) GetSample(c context.Context, id int64, someparam string, anotherParam string) ([]*Sample, error) {
 if c== nil {
 c= context.Background()
 }
 
 ctx, cancel := context.WithTimeout(c, time.Second * 2)
 defer cancel()
 chanSample := make(chan sampleChannel, 3)
 defer close(chanSample)
 go func() {
 chanSample <- u.getDataFromGoogle(ctx, id, anotherParam) // just example of function
 }()
 
 go func() {
 chanSample <- u.getDataFromFacebook(ctx, id, anotherParam)
 }()
 
 go func() {
 chanSample <- u.getDataFromTwitter(ctx, id,anotherParam)
 }()
 
 result := make([]*feed.Feed, 0)
 for loop := 0; loop < 3; loop++ {
 select {
 case sampleItem := <-chanSample:
 if sampleItem.Err != nil {
 continue
 }
 if feedItem.Data == nil {
 continue
 }
 result = append(result,sampleItem.Data)
 // ============================================================
 // CATCH IF THE CONTEXT ALREADY EXCEEDED THE TIMEOUT
 // FOR AVOID INCONSISTENT DATA, WE JUST SENT EMPTY ARRAY TO
 // USER AND ERROR MESSAGE
 // ============================================================
 case <-ctx.Done(): // To get the notify signal that the context already exceeded the timeout
 err := fmt.Errorf("Timeout to get sample id: %d. ", id)
 result = make([]*sample, 0)
 return result, err
 }
 }
 
 return result, nil;
}复制代码

func ( u *usecase) getDataFromFacebook(ctx context.Context, id int64, param string) sampleChanel {
 req, err := http.NewRequest("GET", "https://facebook.com", nil)
 if err != nil {
 return sampleChannel{
 Err: err,
 }
 }
 // ============================================================
 // THEN WE PASS THE CONTEXT TO OUR REQUEST.
 // THIS FEATURE CAN BE USED FROM GO 1.7
 // ============================================================
 if ctx != nil {
 req = req.WithContext(ctx) // NOTICE THIS. WE ARE USING CONTEXT TO OUR HTTP CALL REQUEST
 }
 resp, err := u.httpClient.Do(req)
 if err != nil {
 return sampleChannel{
 Err: err,
 }
 }
 body, err := ioutils.ReadAll(resp.Body)
 if err != nil {
 return sampleChannel{
 Err: err,
 }
 sample := new(Sample)
 err := json.Unmarshall(body, &sample)
 if err != nil {
 return sampleChannle{
 Err: err,
 }
 }
 return sampleChannel{
 Err: nil,
 Data: sample,
 }
 }
}复制代码

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本文来自:掘金

感谢作者:John1314

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