Messaging API 429 errors during JMeter load test

General Discussion
1

Just noticed that the /api/v2/messaging/conversations endpoint returns HTTP 429 Too Many Requests when JMeter pushes 200 concurrent messages to Genesys Cloud US1. The rate limit headers show X-RateLimit-Remaining hitting zero quickly. Are there specific throttle settings for digital channels under load that differ from voice?

2

Check your request batching.

Cause: Zendesk handled high volume via queued jobs, but GC’s messaging API is strictly rate-limited per tenant. You’re hitting the ceiling because each JMeter thread fires a separate API call instead of bundling them.

Solution: Switch to the bulk create endpoint or implement exponential backoff in your JMeter script. Don’t fight the throttle; work with it.

1 Like
3

don’t just add backoff and call it a day. the bigger issue is that you’re likely treating messaging like a fire-and-forget voice leg. in Twilio, the TwiML response handled the session state, but here in GC, if you’re creating the conversation and then immediately firing off the message in the same thread without waiting for the 201 Created or checking the conversation status, you’ll race the backend.

the 429 isn’t just about total QPS, it’s about how you’re hammering the POST /api/v2/messaging/conversations endpoint. if you’re using the JS SDK or raw HTTP, you need to ensure the client isn’t holding open connections that aren’t being reused properly, which adds handshake overhead to the rate limit calculation.

try this pattern in your JMeter HTTP Request defaults or pre-processor. force the connection management to behave, and add a small delay between the conversation creation and the message send.

// Example of how to handle the sequence in a Data Action or external script
// to avoid the race condition that triggers aggressive throttling

async function sendMessageSafe(toNumber, body) {
 const client = PureCloudPlatformClientV2.ApiClient.instance;

 // 1. Create Conversation
 const convBody = {
 to: [{ address: toNumber, type: 'SMS' }],
 from: { address: 'your_verified_sender_id', type: 'SMS' },
 type: 'SMS'
 };

 let conv = await client.MessagingApi.postMessagingConversations(convBody);

 // 2. CRITICAL: Wait for the conversation to be fully initialized
 // without this, the next call might hit a transient state or rate limit
 await new Promise(r => setTimeout(r, 200)); 

 // 3. Send Message
 const msgBody = {
 text: body,
 to: [{ address: toNumber, type: 'SMS' }]
 };

 return await client.MessagingApi.postMessagingConversationsMessages(
 conv.id, 
 msgBody
 );
}

also check your X-RateLimit-Reset header. if it’s not aligning with your JMeter ramp-up, you’re just piling up errors. the US1 region has strict burst limits for messaging endpoints. 200 concurrent threads is too aggressive for a straight POST without queuing. drop it to 50 and see if the 429s disappear. if they do, it’s a burst issue, not a ceiling issue.

2 Likes
4

batching helps, but the real fix is handling the 429 properly. don’t just backoff blindly. parse the retry-after header.

retry = int(response.headers.get('retry-after', 1))
time.sleep(retry)

jmeter needs to respect that delay or you’ll get banned. also, check your tenant’s specific limits. us1 is tighter than eu1.

5

batching is good advice, but don’t ignore the retry-after header. ignoring it gets you throttled harder.

sleep(int(resp.headers.get('retry-after', 1)))

us1 limits are tighter than eu1. respect the delay or you’ll hit a ban.