This is why RCU, aka Read-Copy-Update, exists. RCU avoids the expensive synchronization part by delaying the release of the older version of the data structure

This is why RCU, aka Read-Copy-Update, exists. RCU avoids the expensive synchronization part by delaying the release of the older version of the data structure until a point at which all CPUs are guaranteed to see the new version of the data. The patents have now expired, so it's worth investigating for people that need to write high performance multithreaded code that hits certain shared data structures really hard.