Limit CPU usage of actions (or all sandboxed operations)

[prashantv]

Description of the problem / feature request:

Ability to limit CPU usage of a single action to a single core.

Feature requests: what underlying problem are you trying to solve with this feature?

By default, bazel runs multiple actions in parallel, with concurrency determined by number of cores available. This has an implicit assumption that actions use a single core, but it's possible for actions to use more cores, which can end up negatively affecting other tests, as they may be CPU starved.

Ideally, bazel would set CPU limits such that a single action is limited to 1 core.

What operating system are you running Bazel on?

Linux 4.14 and 4.19

What's the output of bazel info release?

release 3.0.0

Have you found anything relevant by searching the web?

No, most of the resources I've found are about increasing the number of parallel jobs, or performance of the sandbox.

[jwnimmer-tri]

Possibly related to #3688 and #6477.

[susinmotion]

@jin is this related to any of the work you're doing?

[jin]

Not quite, I was more interested in restricting the degree of parallelism for a subset of actions, assuming they all use a single core each.

[susinmotion]

Gotcha, thanks.

[jmmv]

I think this is actually a dup of #10443. Just as we should allow actions to use more threads if possible, we should also limit them when not. Will add a note there.