statistics: remove mutex in hotPeerCache (#3721)

[ti-chi-bot]

This is an automated cherry-pick of #3721

Signed-off-by: yisaer [email protected]

try to remove mutex

Signed-off-by: yisaer [email protected]

What problem does this PR solve?

We use mutex in hotPeerCache which may cause mutex contention.

What is changed and how it works?

This request remove the mutex and refactor flowItem with a proper way.

Tests

I used pd-heartbeat-bench to test pd heartbeat (1 server / 6 cpu), here is the result

v5.0.0

Update speed of each category:
  Requests/sec:      8263.3143
  Save-Tree/sec:        0.0000
  Save-KV/sec:          0.0000
  Save-Space/sec:       0.0000
  Save-Flow/sec:     4131.6572
  Skip/sec:          4131.6572

master

Update speed of each category:
  Requests/sec:      6137.2065
  Save-Tree/sec:        0.0000
  Save-KV/sec:          0.0000
  Save-Space/sec:       0.0000
  Save-Flow/sec:     3068.6033
  Skip/sec:          3068.6033

This request

Update speed of each category:
  Requests/sec:     10228.7168
  Save-Tree/sec:        0.0000
  Save-KV/sec:          0.0000
  Save-Space/sec:       0.0000
  Save-Flow/sec:     5114.3584
  Skip/sec:          5114.3584

Release note

None

[nolouch]

@Yisaer DCO failed.

[Yisaer]

/merge

[ti-chi-bot]

@Yisaer: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

@Yisaer: /merge in this pull request requires 2 approval(s).

In response to this:

/merge

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[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• Yisaer
• nolouch

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After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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[Yisaer]

/merge

[ti-chi-bot]

@Yisaer: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 61fac00

[Yisaer]

/run-integration-common-test

[codecov]

Codecov Report

Merging #3751 (74d221f) into release-5.1 (deec776) will increase coverage by 0.19%.
The diff coverage is 82.44%.

@@               Coverage Diff               @@
##           release-5.1    #3751      +/-   ##
===============================================
+ Coverage        74.93%   75.13%   +0.19%     
===============================================
  Files              244      245       +1     
  Lines            24504    24544      +40     
===============================================
+ Hits             18363    18441      +78     
+ Misses            4510     4487      -23     
+ Partials          1631     1616      -15     

Flag	Coverage Δ
unittests	75.13% <82.44%> (+0.19%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
server/statistics/hot_peer_cache.go	95.65% <ø> (-0.20%)	⬇️
server/statistics/hot_cache_task.go	75.43% <75.43%> (ø)
server/statistics/hot_cache.go	87.23% <85.71%> (-9.51%)	⬇️
pkg/mock/mockcluster/mockcluster.go	95.71% <100.00%> (+0.01%)	⬆️
server/cluster/cluster.go	83.39% <100.00%> (+0.54%)	⬆️
server/statistics/hotstat.go	100.00% <100.00%> (ø)
server/schedule/region_scatterer.go	83.72% <0.00%> (-4.66%)	⬇️
server/election/leadership.go	85.88% <0.00%> (-1.18%)	⬇️
server/schedule/operator/step.go	67.44% <0.00%> (-1.00%)	⬇️
server/grpc_service.go	47.54% <0.00%> (-0.23%)	⬇️
... and 15 more

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