How a flaky test exposed a Redis use-after-free
Summary
An OSS debugging story that reveals how a flaky test exposed a heap use-after-free in the redis-client Ruby gem. The investigation used AddressSanitizer (ASAN) to identify memory corruption and traced it to the hiredis C extension, leading to an upstream fix and changes to test environments. The article demonstrates practical techniques for diagnosing non-deterministic bugs in complex CI stacks and emphasizes robust tooling and collaboration.