add --concurrent-cron-job-syncs flag for kube-controller-manager

[borgerli]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Some clients use cronjob heavily and run >5000 cronjobs in a cluster. The default worker number of 5 is quite not enough in such case.
Whith this PR, they can set desired number of workers of cronjob controller by --concurrent-cron-job-syncs flag.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Add '--concurrent-cron-job-syncs' flag for kube-controller-manager to set the number of workers for cron job controller

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @borgerli. Thanks for your PR.

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[cici37]

/sig apps
/remove-sig api-machinery

[borgerli]

@feiskyer @thockin could you please have a look? thanks.

[alculquicondor]

/ok-to-test

[alculquicondor]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: aae60187eaa7f847a1850886e9847eb9056cd705

[dims]

Looks very similar to what we have before: "concurrent-job-syncs"

kubernetes/cmd/kube-controller-manager/app/options/jobcontroller.go

Line 38 in 9d231f8

fs.Int32Var(&o.ConcurrentJobSyncs, "concurrent-job-syncs", o.ConcurrentJobSyncs, "The number of job objects that are allowed to sync concurrently. Larger number = more responsive jobs, but more CPU (and network) load")

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: borgerli, dims

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• cmd/kube-controller-manager/OWNERS [dims]

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