Worked on stabilizing the Celeborn test suite in the apache/celeborn repository by addressing a NullPointerException in the tryWithTimeoutAndCallback method. Implemented a fallback thread pool to handle cases where deviceCheckThreadPool was uninitialized, ensuring reliable test execution in both isolated and full suite runs. This fix improved continuous integration reliability and reduced flaky test failures without altering production behavior. The work demonstrated a strong grasp of Scala, thread management, and unit testing practices, focusing on test harness hardening and robust multithreading patterns. All changes were validated through comprehensive test reruns, resulting in faster iteration and increased confidence in CI outcomes.