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blocking sync load take too much time. #57710

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@hawkingrei

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1. Minimal reproduce step (Required)

In order to reproduce the problem easily locally, it is recommended to reduce the configuration file parameter stats-load-queue-size and the system variable tidb_stats_load_sync_wait. It is easier to reproduce the problem if you adjust them to 10 and 1 respectively.
You only need to trigger a large number of fast stats sync load tasks to trigger this problem. I have 2,000 tables locally, each with 20 columns and 20 indexes. Using a script to quickly access all columns of all tables can trigger the problem. The SQL example is as follows.

SELECT * FROM %s WHERE c1 = 1 AND c2 = 2 AND c3 = 3 AND c4 = 4 AND c5 = 5 AND c6 = 6 AND c7 = 7 AND c8 = 8 AND c9 = 9 AND c10 = 10 AND c11 = 1 AND c12 = 2 AND c13 = 3 AND c14 = 4 AND c15 = 5 AND c16 = 6 AND c17 = 7 AND c18 = 8 AND c19 = 9 AND c20 = 10

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

no any time

3. What did you see instead (Required)

Image

4. What is your TiDB version? (Required)

v8.1.0

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    affects-6.5This bug affects the 6.5.x(LTS) versions.affects-7.1This bug affects the 7.1.x(LTS) versions.affects-7.5This bug affects the 7.5.x(LTS) versions.affects-8.1This bug affects the 8.1.x(LTS) versions.affects-8.5This bug affects the 8.5.x(LTS) versions.severity/majorsig/plannerSIG: Plannertype/bugThe issue is confirmed as a bug.

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