Architectural Breakdown: We fixed the eval platform we're competing on: a TypeError that crashed thr
We Fixed the Eval Platform: The TypeError That Took Down Three Benchmark Pipelines At 3 AM, Sentry lit up with TypeError: Cannot read property 'map' of undefined . Three benchmark pipelines crashed. Not a memory leak, not a segfault, but a race condition hiding behind a TypeError, turning a high-stakes eval run into chaos. Here is how we resolved it, with no fluff. The Root Cause: Async Data…
Three benchmark pipelines crashed at 3 AM due to a TypeError that occurred in the eval platform. The issue stemmed from a race condition involving asynchronous data and a .map() operation. The async fetchBenchmarkData() function and the sync evaluatePipeline() function were running concurrently, causing the .map() to sometimes encounter undefined inputData.metrics.
This resulted in the TypeError: Cannot read property 'map' of undefined. The error occurred at evaluator.ts:42, where the code assumed the inputData.metrics property would always be present. The junior developer had tested the code with clean data, but in production, the asynchronous fetching of metrics led to the undefined issue. The root cause lay in a race condition between async and sync operations.
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