Can anyone explain why the Genesys Cloud OAuth token endpoint starts returning 401 Unauthorized errors specifically when we ramp up concurrent API calls from our JMeter script? We are running a load test for a custom integration that polls the /api/v2/telephony.phonelines endpoint every 5 seconds for 500 agents. The initial token acquisition works fine, but after about 15 minutes of steady state, the refresh token flow starts failing.
We are using the standard client credentials grant type. The JMeter config has 50 threads looping indefinitely. Each thread maintains its own session and attempts to refresh the token when it detects expiration. The error response body usually contains:
{
"code": "bad_request",
"message": "The refresh token is invalid or expired",
"status": 401
}
This is happening in the APAC region. We suspect it might be related to the rate limits on the authentication service itself, rather than the main API endpoints. We have checked the X-RateLimit-Remaining headers on the main API calls, and they are healthy. However, we are not seeing specific rate limit headers on the /oauth/token endpoint.
Is there a specific concurrency limit for token refreshes per client ID? We are hitting roughly 2-3 refresh requests per second across all threads. This seems low, but the failures are consistent. We tried adding a random delay of 100-500ms between refresh attempts, which reduced the error rate but did not eliminate it. The errors seem to cluster around the exact minute mark of the hour.
We are using the Java SDK version 12.1.0 for our integration logic, but the load test is raw HTTP via JMeter. Any insights into how the auth service handles bursty refresh requests from a single client ID would be appreciated. We need to ensure our integration can handle scaling to 1000 agents without auth failures causing data gaps.
It depends, but generally… this behavior often stems from how the application handles token lifecycle management under concurrent load rather than a Genesys Cloud API limitation. When polling /api/v2/telephony.phonelines every 5 seconds for 500 agents, you are generating significant request volume. If your integration logic attempts to refresh the token for every individual request that receives a 401, you create a race condition where multiple threads try to refresh simultaneously, invalidating previous tokens or hitting rate limits on the auth endpoint.
The standard approach is to implement a centralized token cache with a single writer pattern. Do not let each API call independently decide to refresh. Instead, maintain a shared token object. When a 401 is received, only the first thread should initiate the refresh. Subsequent threads waiting for a valid token should block until the new token is acquired. Here is a conceptual flow for the refresh logic:
let currentToken = null;
let isRefreshing = false;
let refreshPromise = null;
async function getToken() {
if (currentToken && !currentToken.isExpired()) {
return currentToken;
}
if (!isRefreshing) {
isRefreshing = true;
refreshPromise = refreshAccessToken(); // Your refresh logic
currentToken = await refreshPromise;
isRefreshing = false;
refreshPromise = null;
} else {
// Wait for the ongoing refresh to complete
currentToken = await refreshPromise;
}
return currentToken;
}
Be careful with thread safety in your specific runtime environment, as concurrent writes to the token store can cause corruption. Also, verify that your client credentials are not being throttled by the identity provider. In multi-org setups, strict tenant isolation can sometimes cause unexpected 401s if the token scope is slightly off, but the concurrency issue is usually the primary culprit here. Check your logs for duplicate refresh requests occurring within milliseconds of each other.
The way I solve this is by locking the refresh call in JMeter so only one thread handles the token update.
The race condition causes parallel requests to use invalid tokens, triggering the 401 errors.