Userspace RCU

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.

liburcu-cds provides efficient data structures based on RCU and lock-free algorithms. Those structures include hash tables, queues, stacks, and doubly-linked lists.

The liburcu project has been started by Mathieu Desnoyers.


Binary packages

liburcu is available as a Debian package named liburcu1. The development files are available in package liburcu-dev.

A package is also available on Arch Linux in the AUR.


Packages are available at :


The source code can be browsed at :

The library is available for download in this git repository :

  • git clone git://

Mailing list

For help and developer discussions, see the LTTng mailing list.

To the question "why is this hosted on the LTTng website ?", the answer is : the userspace RCU library was needed for the LTTng userspace tracer port. The userspace tracer implementation is therefore the motivation and first user of liburcu.

Other projects using liburcu

  • Knot DNS : Knot DNS is a high-performance authoritative-only DNS server.
  • Netsniff-ng : Netsniff-ng i