Unstable test tidbTestTopSQLSuite.TestTopSQLAgent

[zhouqiang-cl]

Bug Report

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[2021-06-14T13:28:24.499Z] ----------------------------------------------------------------------
[2021-06-14T13:28:24.499Z] FAIL: tidb_test.go:1379: tidbTestTopSQLSuite.TestTopSQLAgent
[2021-06-14T13:28:24.499Z] 
[2021-06-14T13:28:24.499Z] tidb_test.go:1498:
[2021-06-14T13:28:24.499Z]     checkFn(0)
[2021-06-14T13:28:24.499Z] tidb_test.go:1423:
[2021-06-14T13:28:24.499Z]     c.Assert(len(records), Equals, n)
[2021-06-14T13:28:24.499Z] ... obtained int = 5
[2021-06-14T13:28:24.499Z] ... expected int = 0

1. Minimal reproduce step (Required)

in ci https://ci.pingcap.net/blue/rest/organizations/jenkins/pipelines/tidb-unit-test-nightly/runs/655/nodes/127/steps/496/log/?start=0

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

master a45b3aa

[breezewish]

@crazycs520 PTAL

[ti-srebot]

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