Senior LevelLinux Commands & SysAdmin
What is the Cgroup Freezer subsystem and how does it suspend running process trees?
❓ Interview Prompt: Explain Cgroup Freezer subsystem, freezing process execution states (FROZEN), unfreezing (THAWED), and container checkpointing.
The Cgroup Freezer subsystem provides the ability to pause (freeze) and resume (thaw) execution for an entire group of processes simultaneously:
How it Works:
Writing 'FROZEN' to 'cgroup.freeze' transitions all member processes into uninterruptible sleep without sending SIGSTOP signals.
•
Essential for container snapshotting, live migration, and CRIU checkpointing!
Code Implementation Example
bash
# Freeze all processes inside container cgroup
echo 1 | sudo tee /sys/fs/cgroup/docker/container-id/cgroup.freeze
# Resume (thaw) frozen container process tree
echo 0 | sudo tee /sys/fs/cgroup/docker/container-id/cgroup.freeze💡Freezing and thawing process trees using Cgroups v2 freezer controller.
🎯 Interview Key Takeaway
Use Cgroup Freezer to pause process trees atomically during container checkpointing and live migration.
#Cgroup Freezer#Containers#Checkpointing#Senior
Back to all Linux Commands & SysAdmin Questions→