USER-LEVEL READ-COPY UPDATE THAT DOES NOT REQUIRE DISABLING PREEMPTION OR SIGNAL HANDLING

A user-level read-copy update (RCU) technique. A user-level RCU subsystem executes within threads of a user-level multithreaded application. The multithreaded application may include reader threads that read RCU-protected data elements in a shared memory and updater threads that update such data elements. The reader and updater threads may be preemptible and comprise signal handlers that process signals. Reader registration and unregistration components in the RCU subsystem respectively register and unregister the reader threads for RCU critical section processing. These operations are performed while the reader threads remain preemptible and with their signal handlers being operational. A grace period detection component in the RCU subsystem considers a registration status of the reader threads and determines when it is safe to perform RCU second-phase update processing to remove stale versions of updated data elements that are being referenced by the reader threads, or take other RCU second-phase update processing actions.