Checkpoint-Restore Hits v1.0: Freeze Your Linux Apps

The Checkpoint-Restore Tool has reached version 1.0 as part of the CRIU project. Checkpoint/Restore In Userspace allows for users to freeze running applications and checkpoint it to the hard drive as a file and that checkpoint can then be restored to a running process later on. CRIU is different from suspend-and-resume with the Linux kernel in that this is a tool for handling individual programs and it is implemented in user-space.

After the last of the necessary Linux kernel patches landed upstream a few months back, CRIU developers have been working on improving the user-space Checkpoint-Restore tool. They're now happy to declare it version 1.0, per the mailing list announcement.

The CRIU user-space utility allows producing checkpoint dumps, restoring checkpointed processes, decoding dumped binary files, checking on kernel support, executing a system call from another task's context, and also launching as a RPC service. While they pride it on being a user-space utility, it's not without its fair share of kernel configuration options that must be enabled for the checkpoint/restore process to work.

Among the use-cases out of the project for CRIU include speeding up slow-boot services by using checkpoints after reboots, reboot-less kernel upgrades, network load balancing by moving applications between systems, HPC improvements, desktop environment suspend/resume, process duplication, save support for apps/games that otherwise do not support in-game saving, and better debugging of hung applications. Among the tested software that is known to work well with CRIU's check-pointing and process restoration includes make, GCC, tar/bz2, Apache, MySQL. SSHD, Java, NGINX, MongoDB, iperf, and OpenVPN.

For more information on the Checkpoint-Restore utility, visit CRIU.org. CRIU is part of the OpenVZ project and is sponsored by the Parallels virtualization software company.