Looking for some advice on troubleshooting this persistent issue we are hitting during our performance validation phase for the work force management module.
we are running a jmeter 5.6.2 load test against the us-east region to determine the maximum throughput for bulk schedule imports. the goal is to simulate a peak load scenario where multiple supervisors are uploading shifts simultaneously.
our test configuration uses 100 virtual users hitting the post /api/v2/wfm/schedule/import endpoint. each request contains a json payload with approximately 500 shift records, totaling roughly 150kb per request. the requests are spaced 2 seconds apart per user to mimic realistic human behavior, resulting in a sustained load of about 50 requests per second.
initially, the system handles the load without issue. however, after approximately 45 seconds of continuous operation, we start seeing intermittent 502 bad gateway errors. the error rate climbs to about 15% within the next minute before the gateway times out completely, returning 504 gateway timeout errors for all subsequent requests.
we have verified that the api keys are valid and have not hit the standard rate limit headers, as the response headers show x-ratelimit-remaining values that are still positive. the issue seems to correlate with the cumulative number of concurrent websocket connections or backend processing threads rather than a simple rate limit cap.
has anyone encountered similar gateway failures when pushing high-volume schedule imports? we are wondering if there is a known threshold for concurrent import jobs that triggers a backend circuit breaker or if we need to adjust our payload chunking strategy. any insights on the internal capacity limits for this specific endpoint would be appreciated. we are currently blocked on our capacity planning report and need to understand if this is a configuration issue on our side or a platform limitation.
Check your payload chunking strategy and retry logic in your JMeter test plan. A 502 Bad Gateway during bulk WFM imports usually indicates that the load balancer or API gateway is dropping connections because individual requests are too large or are timing out before the server can process them. Instead of sending the entire week’s schedule for 100 agents in a single JSON blob, break the import into smaller batches of 10-20 agents per request. This reduces the memory footprint on the server side and prevents the connection from being killed prematurely. You can automate this splitting in your pre-processor script by iterating through the agent list and creating separate POST calls.
Another critical factor is the concurrency limit for the specific endpoint. The WFM schedule import API has stricter rate limits compared to simple data queries. If 100 virtual users are hammering the endpoint simultaneously, you are likely hitting a hard throttle that results in gateway errors. Try implementing an exponential backoff mechanism in your JMeter thread group. Set the initial retry delay to 1 second, doubling it with each subsequent failure up to a maximum of 5 retries. This approach allows the system to catch up with the queue rather than flooding it with repeated failed attempts. Also, ensure your user agent string in the test headers matches standard browser or SDK identifiers, as some gateways inspect these for traffic shaping. By reducing batch size and adding intelligent retries, you should see a significant drop in 502 errors and a more accurate representation of sustainable throughput for your Chicago team’s weekly publishing workflow.
Oh, this is a known issue… the batch size recommendation is spot on. also ensure your oauth token refresh logic isn’t causing race conditions during the high concurrency phase, as that often triggers 502s alongside the gateway timeouts.
Have you checked if your BYOC trunks are interfering with the WFM API gateway? The 502s might be caused by shared infrastructure limits during high concurrency.