[Provider/Azure] optimize mutex locks

[gaurav1086]

What type of PR is this?

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/kind api-change
/kind bug
/kind cleanup
/kind deprecation
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:
azure.go : use read lock when possible to allow other goroutines to read shared data concurrently.
Which issue(s) this PR fixes:

Fixes #
N/A
Special notes for your reviewer:
N/A
Does this PR introduce a user-facing change?:

NONE

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

NONE

[k8s-ci-robot]

Hi @gaurav1086. Thanks for your PR.

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[gaurav1086]

/assign @feiskyer

[gaurav1086]

cc @andyzhangx

[andyzhangx]

/ok-to-test

[andyzhangx]

/kind bug
/priority important-soon
/sig cloud-provider
/area provider/azure

[feiskyer]

@gaurav1086 Could you clarify the issues this PR wants to fix? have you seen performance issues with current lock?

[gaurav1086]

@feiskyer no issues. Just a proposal to enhance performance since theoretically rlock allows concurrent reading as opposed to a vanilla lock.

[feiskyer]

@feiskyer no issues. Just a proposal to enhance performance since theoretically rlock allows concurrent reading as opposed to a vanilla lock.

OK, thanks. The change looks good.

/retest
/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: feiskyer, gaurav1086

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• staging/src/k8s.io/legacy-cloud-providers/azure/OWNERS [feiskyer]

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[fejta-bot]

/retest
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