How to Use CRIU for Linux Process Checkpoint and Restore with Node.js

CRIU (Checkpoint/Restore In Userspace) is a Linux userspace tool that can checkpoint and restore processes, enabling scenarios such as hot migration, startup acceleration, and debugging.

Install CRIU

On CentOS 7, installation is straightforward:

yum install criu

Write a Test Node.js Program

Create index.js in ~/test. The program prints its PID and an incrementing number every second:

let idx = 0;
(async () => {
  while (true) {
    console.log(process.pid, idx++);
    await sleep(1000);
  }
})().catch(console.error);

function sleep(n) {
  return new Promise(resolve => {
    setTimeout(resolve, n);
  });
}

Running the program produces output like:

node test.js
3501 0
3501 1
3501 2
...

Create a Snapshot

Assuming the process PID is 3501, create a checkpoint snapshot: criu dump -j -t 3501 -D ~/testSnapshot The -j flag indicates shell jobs, -t specifies the target PID, and -D sets the directory where the snapshot is stored. After the dump, the process terminates.

Restore the Process

To restore the checkpointed process, run: criu restore -j -D ~/testSnapshot The process resumes with the counter continuing from its previous value, e.g.:

3501 37
3501 38
...

Conclusion

This simple example demonstrates CRIU's capability to checkpoint and restore a running Node.js process, illustrating its potential for use cases such as process migration and rapid startup. For more details, see the original article "Usage scenarios‑CRIU".