From Global to Local Quiescence: Wait-Free Code Patching of Multi-Threaded Processes

Explore a groundbreaking approach to live patching multi-threaded processes in this 19-minute conference talk from OSDI '20. Learn about WfPatch, a wait-free method that allows for code changes to be injected into running programs without requiring global quiescence. Discover how this technique can be applied gradually to individual threads at local points of quiescence, enabling uninterrupted progress for other threads. Examine the implementation of WfPatch as a kernel service and user-space library for Linux 5.1, and review its evaluation with popular software like OpenLDAP, Apache, Memcached, Samba, Node.js, and MariaDB. Gain insights into the successful application of 33 different binary patches, including 15 critical updates, without noticeable increases in request latencies. Compare the performance benefits of WfPatch to traditional global quiescence methods, particularly in high-load scenarios.