Goroutines一会儿不回复

Question

I initialize a goroutine as a worker, to continuously receive messages from aws sqs.

The worker works like a charm until there are no message receive from sqs queue. The worker seem to lost (unresponsive).

Is the problem relative to GC? Anyone encounter this problem?

Here is simple code https://play.golang.org/p/CuyvUy7b_Sf .

Updated:

func main() {
    // Init router
    // Handling some APIs
    // ...
}

func userWorker() {
    sqsClient := getSqsClient()
    for {
        result, err := sqsClient.ReceiveMessage(&sqs.ReceiveMessageInput{
            QueueUrl:            aws.String(queueURL),,
            MaxNumberOfMessages: aws.Int64(1),
            MessageAttributeNames: aws.StringSlice([]string{
                "All",
            }),
            WaitTimeSeconds: aws.Int64(1), // wait for seconds
        })
        if err != nil {
            log.Printf("Unable to receive message from sqs queue  %v.", err)
            continue
        }

        if len(result.Messages) > 0 {
            if result.Messages[0].MessageAttributes["payload"] != nil {
                // extract payload
                messagePayload := result.Messages[0].MessageAttributes["payload"].BinaryValue
                var payload schema.UsersWorkerPayload
                err = msgpack.Unmarshal(messagePayload, &payload)
                if err != nil {
                    log.Printf("Error when msgpack decodes payload %v", err)
                    continue
                }

                // get devices tokens from userIDs
                tokenIDs, err := db.GetTokenIdByUsers(payload.UserIds)
                if err != nil {
                    log.Printf("userWorker error GetTokenIdByUsers %v", err)
                    continue
                }
                if len(tokenIDs) == 0 {
                    log.Println("Could not get token ID.")
                    continue
                }

                results, err := fcm.PushToTokenIDs(tokenIDs, payload.Payload)
                if err != nil {
                    log.Printf("userWorker PushToTokenIDs error %v", err)
                    continue
                } else {
                    // delete message if everything is ok
                    err = mrsqs.DeleteMessage(config.UserQueueName, result.Messages[0].ReceiptHandle)
                    if err != nil {
                        log.Printf("Error when delete sqs message %v", err)
                    }
                }
            }
        }
    }
}

func init() {
    go userWorker()
}

Answer 1

This program will exit immediately after the fmt.Println("Hello, playground") command is complete. You can use the wait group or a channel to keep the goroutine running.

func main() {
    go userWorker()
    c := make(chan struct{})
    <-c
}

func userWorker() {
...
}