podman pause vs podman stop: what's the difference?

Question

podman pause is listed as "pause a container" in --help, while podman stop is listed as "stop a container" what's the difference between these two commands?

Answer 1

This functionality is left to the ContainerEngine for implementation.

Pause is suspend

Pause does some voodoo with freezing cgroups you can see this in the code to crun in libcrun_cgroup_pause_unpause_with_mode (which handles pause and unpause). Tasks do not know when they're frozen it happens in the kernel, according to the docs on cgroup v1's freeze,

In contrast, the cgroup freezer uses the kernel freezer code to prevent the freeze/unfreeze cycle from becoming visible to the tasks being frozen. This allows the bash example above and gdb to run as expected.

Pause set the container's cgroup status to thawed, freezing, or frozen.

Stop kills

Stop will send SIGKILL or SIGINT depending on if there is a timeout. This functionality is not in crun but in podman (confirmed by checking man crun and in source).