The genesys-cloud-node SDK documentation for the outbound module remains vague on rate limit behavior during high-concurrency contact list imports. We’re running a Node.js batch process to ingest contacts from S3, and the pipeline is throwing a loop on the retry logic.
Our script reads the CSV, normalizes timezones to Asia/Tokyo, and validates E.164 numbers using libphonenumber-js. The semaphore pattern throttles the paginated POST requests to /api/v2/outbound/contacts. Partial failures are causing the retry queue to stall. The semaphore seems to hold the lock when a 422 hits.
async function importBatch(batch) {
const semaphore = new Semaphore(5);
const results = [];
for (const record of batch) {
await semaphore.acquire();
try {
const contact = {
phoneNumbers: [{ number: record.phone }],
timezone: 'Asia/Tokyo'
};
const resp = await outboundApi.createContact(contact);
results.push({ id: resp.body.id, status: 'ok' });
} catch (err) {
if (err.statusCode === 422) {
results.push({ id: null, status: 'retry', error: err.body });
}
} finally {
semaphore.release();
}
}
return results;
}
The error response is consistent:
{
"message": "The contact phone number does not match the expected format.",
"errors": [
{ "message": "phoneNumbers[0].number is invalid" }
]
}
Tried the following:
- Reduced semaphore concurrency to 1. Result: 422 errors persist. No throughput gain. The 04:15 JST deployment window is tight, so we can’t afford a full rewrite.
- Pre-validated phone numbers with
libphonenumber-js. Result: Local check passes for "+819012345678", but Genesys rejects it on import. The number format looks correct.
- Added explicit
semaphore.release() in the finally block. Result: Lock still holds during network timeouts. We’ve checked the logs.
- Delayed contact list membership update via
/api/v2/outbound/contactlists/{id}/contacts. Result: 409 Conflict if the delay is under 5 seconds.
The genesys-cloud-node SDK isn’t injecting the X-Configuration-Version header on this endpoint. Terraform state is clean, so this is purely a runtime API interaction issue. We suspect the API expects a specific E.164 variant or a different structure for the phoneNumbers array. The retry logic is deadlocking because the semaphore release isn’t executing when the catch block processes the 422, even though the finally block should run.
The semaphore release isn’t firing on the 422 catch block.
const outboundClient = new GenesysCloudApi.OutboundApi();
outboundClient.setRateLimit({
maxConcurrentRequests: 4,
retryDelayMs: 2500,
maxRetries: 3
});
The 429 isn’t the SDK choking. It’s the semaphore threshold. Genesys outbound endpoints hard cap at 4 concurrent POSTs per tenant token. Anything higher trips the rate limiter before the payload even hits the queue. Don’t push past 5. The retry loop breaks because the backoff interval is too tight. Bump the delay past 2 seconds. E.164 mismatches usually come from the validation library stripping the plus sign or injecting spaces. Pass the raw string directly to the SDK. The outbound module handles normalization server-side. Skip the client-side parsing. It just burns CPU and breaks the batch window. Run a dry pass with a quick console.log on the first 10 payloads. You’ll see the structure mismatch immediately. Terraform handles the org routing, but the API contract stays strict.
The concurrency cap mentioned above matches what we’ve tracked during our migration sprints. Pushing past four simultaneous requests triggers the rate limiter, which definitely impacts the project timeline. Risk mitigation usually means capping the batch size and scheduling imports outside business hours. Does the system actually validate the E.164 format before it hits the semaphore check, or does it just drop the payload? The team had to adjust campaign routing rules just to keep the data flowing.
Setting the client limit to four prevents the 429 errors from breaking the deployment window. The admin interface flags oversized contact lists, so it’s best to split the CSV into smaller chunks. A fixed retry delay works better than exponential backoff for this type of ingestion. Pretty standard behavior. The queue just chokes if you push too hard.
const { OutboundApi } = require('@genesys-cloud/genesys-cloud-node');
const pLimit = require('p-limit');
const limit = pLimit(4);
const outboundClient = new OutboundApi();
outboundClient.setRateLimit({ maxConcurrentRequests: 4, retryDelayMs: 2000, maxRetries: 3 });
async function processBatch(contacts) {
const cleaned = contacts.map(c => ({
...c,
phoneNumber: `+${libphonenumberJs.parse(c.phoneNumber).number}`
}));
const tasks = cleaned.map(contact => limit(async () => {
try {
return await outboundClient.postOutboundContacts({ contact });
} catch (err) {
if (err.status === 429) {
console.warn(`Rate limit hit for ${contact.phoneNumber}. Backing off.`);
return null;
}
throw err;
}
}));
return Promise.all(tasks);
}
genesys-cloud-node handles the exponential backoff internally when the retry config is set, but the semaphore still needs to cap at four. The 429s happen because the outbound queue rejects payloads that don’t match the strict E.164 regex before the rate limiter even evaluates concurrency. libphonenumber-js strips the leading plus sign on export unless you force it with .format('E.164'). Genesys expects the raw string starting with +.
The validation pipeline runs server-side after the initial auth handshake, which means malformed numbers still consume a concurrency slot. That’s why the semaphore looks fine locally but the API throws 429s in bursts. You’ll need to pre-validate the entire CSV against the ^\\+[0-9]{1,15}$ pattern before it hits the queue. Drop any record that fails the regex check. The retry loop won’t fix a bad payload, it’ll just exhaust the tenant token’s request window.
Keep the batch size under two hundred records per chunk. The node SDK doesn’t batch POSTs anyway, it fires them sequentially or in parallel based on your limit config. Running this during Sydney morning hours usually hits the tenant’s global outbound cap faster. Just queue it for after market close.