Unable to release memory bytes buffer - go

Question

Go 1.18.1
pprof report
3549.93kB 49.73% 49.73% 3549.93kB 49.73% src/lag_monitor.PublishLagMetricToDataDog
514kB 7.20% 56.93% 514kB 7.20% bufio.NewWriterSize
512.88kB 7.18% 64.11% 512.88kB 7.18% encoding/pem.Decode
512.69kB 7.18% 71.30% 1536.98kB 21.53% crypto/x509.parseCertificate
512.50kB 7.18% 78.48% 512.50kB 7.18% crypto/x509.(*CertPool).AddCert
This piece of code appears to not release memory and based on pprof, the beloew function is the one consuming most memory.Memory graph
func caller() {
events := make([]string, 0)
//....
PublishLagMetricToDataDog(ctx, strings.Join(events, ","))
}
func PublishLagMetricToDataDog(ctx context.Context, events string) error {
msg := `{
"series": [%v]
}`
b := []byte(msg)
resp, err := http.Post("https://api.datadoghq.com/api/v1/series?api_key="+env.GetDataDogKey(), "application/json", bytes.NewBuffer(b))
if err != nil {
logger.Error(ctx, "Error submitting event to datadog, err = ", err)
return err
}
logger.Info(ctx, resp)
return nil
}
Above function is called in a loop. Since there are no global variables, and no reference to the byte slice from PublishLagMetricToDataDog, I am not able to pinpoint the memory leak. I read about Reset() and Truncate(), but this does not release the underlying memory.

Answer 1

You must close the response body for every http response you receive. Not doing so will potentially lead to resource leaks, such as the one you've observed.
Solution:
resp, err := http.Post("https://api.datadoghq.com/api/v1/series?api_key="+env.GetDataDogKey(), "application/json", bytes.NewBuffer(b))
if err != nil {
logger.Error(ctx, "Error submitting event to datadog, err = ", err)
return err
}
logger.Info(ctx, resp)
_ = resp.Body.Close() // <--- Add this
return nil
}