Di Zhao focused on improving test reliability in the facebook/jemalloc repository by addressing a critical bug in the PSSet unit tests. He resolved a SIGSEGV that occurred when large PAGESIZE and hugepages were enabled, migrating stack-allocated arrays to heap allocations using C. This approach ensured proper memory management by freeing allocated memory, which reduced the risk of memory leaks and flaky test failures. His work demonstrated strong debugging and unit testing skills, resulting in more stable and maintainable tests. Over the month, Di contributed depth in diagnosing low-level memory issues and implementing robust solutions to enhance the repository’s test infrastructure.