Concurrent goroutine and WithRetryKey() Usage Leads to Request Discrepancies

[YukiTsuchida]

System Informations

• Go version: 1.22
• OS: All

Expected Behavior

When making multiple PushMessage API requests concurrently using goroutines, each request's X-Line-Retry-Key and message body should match and be sent as expected.

Current Behavior

Using goroutines to invoke the PushMessage API multiple times results in occasional mismatches between the X-Line-Retry-Key and the message content in the request body. This leads to the LINE API mistakenly identifying these requests as duplicates, returning a 409 error, and consequently failing to send some messages.

Steps to Reproduce

https://go.dev/play/p/6idORXgHYJ_s

Logs

Here is an example of the actual request logs, where the mismatch between the X-Line-Retry-Key and the text field in the request body can be confirmed:

POST /v2/bot/message/push HTTP/1.1
Host: 127.0.0.1:36111
Accept-Encoding: gzip
Authorization: Bearer channelToken
Content-Length: 52
Content-Type: application/json; charset=UTF-8
User-Agent: LINE-BotSDK-Go/8.4.0
X-Line-Retry-Key: 1

{"to":"to","messages":[{"type":"text","text":"1"}]}

POST /v2/bot/message/push HTTP/1.1
Host: 127.0.0.1:36111
Accept-Encoding: gzip
Authorization: Bearer channelToken
Content-Length: 52
Content-Type: application/json; charset=UTF-8
User-Agent: LINE-BotSDK-Go/8.4.0
X-Line-Retry-Key: 4

{"to":"to","messages":[{"type":"text","text":"4"}]}

POST /v2/bot/message/push HTTP/1.1
Host: 127.0.0.1:36111
Accept-Encoding: gzip
Authorization: Bearer channelToken
Content-Length: 52
Content-Type: application/json; charset=UTF-8
User-Agent: LINE-BotSDK-Go/8.4.0
X-Line-Retry-Key: 0

{"to":"to","messages":[{"type":"text","text":"0"}]}

POST /v2/bot/message/push HTTP/1.1
Host: 127.0.0.1:36111
Accept-Encoding: gzip
Authorization: Bearer channelToken
Content-Length: 52
Content-Type: application/json; charset=UTF-8
User-Agent: LINE-BotSDK-Go/8.4.0
X-Line-Retry-Key: 2

{"to":"to","messages":[{"type":"text","text":"2"}]}

POST /v2/bot/message/push HTTP/1.1
Host: 127.0.0.1:36111
Accept-Encoding: gzip
Authorization: Bearer channelToken
Content-Length: 52
Content-Type: application/json; charset=UTF-8
User-Agent: LINE-BotSDK-Go/8.4.0
X-Line-Retry-Key: 0                                              <-------- 0 (incorrect)

{"to":"to","messages":[{"type":"text","text":"3"}]}

Additional Context

Currently, I am working around this issue by creating a new instance of linebot.Client for each request, but this is merely a temporary workaround. This approach is not suitable, especially under circumstances of handling large-scale traffic. I am looking forward to a resolution for this problem.

[Yang-33]

Hi, thank you for using line-bot-sdk-go and this report, @YukiTsuchida !

The issue is that this is not thread-safe in setRetryKey

line-bot-sdk-go/linebot/client.go

Lines 294 to 296 in 7bb6882

	func (client *Client) setRetryKey(retryKey string) {
	client.retryKeyID = retryKey
	}

Therefore, creating a new client is one of the solutions. The new client does not seem to have the same issue. Please give it a try.

line-bot-sdk-go/README.md

Lines 149 to 165 in 291a96f

	### Send message ###
	With an ID, you can send message using ```PushMessage()```
	```go
	bot.PushMessage(
	&messaging_api.PushMessageRequest{
	To: "U.......",
	Messages: []messaging_api.MessageInterface{
	messaging_api.TextMessage{
	Text: replyMessage,
	},
	},
	},
	nil, // x-line-retry-key
	)
	```

[YukiTsuchida]

@Yang-33 Thanks for the quick reply! I solved it using the method you provided.
https://go.dev/play/p/Xx4Bk3nTzrY

[Yang-33]

Thank you for trying this yourself~ That's good~