Use EPOLL_CLOEXEC to prevent fd leaks.

[cpuguy83]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind bug

What this PR does / why we need it:

Use EPOLL_CLOEXEC to prevent fd leaks.

Which issue(s) this PR fixes:

Special notes for your reviewer:

There's still an issue with fsnotify which is used in other places.
Reaching out to the maintainer, but he backed out of the project some
time ago and there's no active committers AFAIK.

Does this PR introduce a user-facing change?:

Use O_CLOEXEC to ensure file descriptors do not leak to subprocesses.

[k8s-ci-robot]

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[cpuguy83]

/sig node

[cpuguy83]

/assign @derekwaynecarr

[ddebroy]

/ok-to-test

[khenidak]

/lgtm

[cpuguy83]

/test pull-kubernetes-kubemark-e2e-gce-big

[dims]

/priority important-soon
/retest
/milestone v1.15

[timmycarr]

Hi! Friendly reminder from your release team: we are starting the code freeze for 1.15 tomorrow EOD. Seeing some good progress here, just checking in to see if this is still planned for the 1.15 cycle? See that milestone added a couple of days ago and awaiting a LGTM. Assuming that's the case. Can I get a quick confirmation here?

[soggiest]

@dims Is this release blocking? I see you've approved this PR but it is lacking a LGTM label, I'm inclined to move this to 1.16.

[dims]

@soggiest sounds good, my approval is not enough, need folks from sig-node to approve unfortunately :(

[soggiest]

/milestone v1.16

[dims]

/uncc

[derekwaynecarr]

apologies for the delay, for some reason this PR was lost in my review queue. i assume you were observing leaks from this area, but its not clear at what rate? we should have metrics for this and i am wondering why it hasn't come up prior.

@sjenning can you take a look? i think you were the original author for using memcg notifications in this area, and it would be good for you to weigh in.

[sjenning]

related fsnotify/fsnotify#219
/lgtm
I don't think we are leaking fd's that I know of but this is good hygiene unless you are intentionally wanting to share fd's with child processes (which we don't).
needs a rebase though.

[cpuguy83]

Yes, I went on a hunt for possible leaks after a user reported some issues running out of inotify handles (without much to go on to debug with). These are just what I ran across as possible, and unlikely to want to be shared with sub-processes.

[dims]

@cpuguy83 let's rebase and ping folks for approval again :)

[derekwaynecarr]

thanks @cpuguy83 and @sjenning for commenting.

kubelet changes lgtm.

/approve
/lgtm

[dims]

/assign @thockin @dchen1107

(We need pkg/ OWNERS approval, please see @derekwaynecarr 's /approve above)

[thockin]

Thanks!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpuguy83, derekwaynecarr, thockin

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[fejta-bot]

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