liburcu is a LGPLv2.1 userspace RCU (read-copy-update)
library. This data synchronization library provides
read-side access which scales linearly with the number
of cores. It does so by allowing multiples copies of a
given data structure to live at the same time, and by
monitoring the data structure accesses to detect grace
periods after which memory reclamation is possible.

WWW: http://liburcu.org/