Unstable test testPrepareSerialSuite.TestPrepareOverMaxPreparedStmtCount

[zhouqiang-cl]

Bug Report

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[2021-06-20T18:08:29.567Z] FAIL: prepare_test.go:256: testPrepareSerialSuite.TestPrepareOverMaxPreparedStmtCount

[2021-06-20T18:08:29.567Z] 

[2021-06-20T18:08:29.567Z] prepare_test.go:302:

[2021-06-20T18:08:29.567Z]     ...

[2021-06-20T18:08:29.567Z] /home/jenkins/agent/workspace/tidb-unit-test-nightly/go/src/github.com/pingcap/tidb/util/testleak/leaktest.go:168:

[2021-06-20T18:08:29.568Z]     c.Errorf("Test %s check-count %d appears to have leaked: %v", c.TestName(), cnt, g)

[2021-06-20T18:08:29.568Z] ... Error: Test testPrepareSerialSuite.TestPrepareOverMaxPreparedStmtCount check-count 50 appears to have leaked: github.com/pingcap/tidb/ddl.(*worker).start(0xc161c12070, 0xc0aeeb8000)

[2021-06-20T18:08:29.568Z] 	/home/jenkins/agent/workspace/tidb-unit-test-nightly/go/src/github.com/pingcap/tidb/ddl/ddl_worker.go:157 +0x315

[2021-06-20T18:08:29.568Z] created by github.com/pingcap/tidb/ddl.(*ddl).Start

[2021-06-20T18:08:29.568Z] 	/home/jenkins/agent/workspace/tidb-unit-test-nightly/go/src/github.com/pingcap/tidb/ddl/ddl.go:364 +0x6a5

[2021-06-20T18:08:29.568Z] 

[2021-06-20T18:08:29.568Z] prepare_test.go:302:

[2021-06-20T18:08:29.568Z]     ...

[2021-06-20T18:08:29.568Z] /home/jenkins/agent/workspace/tidb-unit-test-nightly/go/src/github.com/pingcap/tidb/util/testleak/leaktest.go:168:

[2021-06-20T18:08:29.568Z]     c.Errorf("Test %s check-count %d appears to have leaked: %v", c.TestName(), cnt, g)

[2021-06-20T18:08:29.568Z] ... Error: Test testPrepareSerialSuite.TestPrepareOverMaxPreparedStmtCount check-count 50 appears to have leaked: github.com/pingcap/tidb/ddl.(*worker).start(0xc161c120e0, 0xc0aeeb8000)

[2021-06-20T18:08:29.568Z] 	/home/jenkins/agent/workspace/tidb-unit-test-nightly/go/src/github.com/pingcap/tidb/ddl/ddl_worker.go:157 +0x315

[2021-06-20T18:08:29.568Z] created by github.com/pingcap/tidb/ddl.(*ddl).Start

[2021-06-20T18:08:29.568Z] 	/home/jenkins/agent/workspace/tidb-unit-test-nightly/go/src/github.com/pingcap/tidb/ddl/ddl.go:364 +0x6a5

1. Minimal reproduce step (Required)

in ci https://ci.pingcap.net/blue/organizations/jenkins/tidb-unit-test-nightly/detail/tidb-unit-test-nightly/1419/pipeline

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

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

master 712fb1c

[zimulala]

PTAL @bb7133

[ti-srebot]

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