a query with many tasks exceeds the hard limit of threads.

[fzhedu]

Bug Report

Please answer these questions before submitting your issue. Thanks!

tiflash_regression_test_daily
Build Number: 1633
Result: FAILURE ❌
Branch: master
Version: latest
Elapsed Time: 440.69 Mins
Build Link: https://ci.pingcap.net/blue/organizations/jenkins/tiflash_regression_test_daily/detail/tiflash_regression_test_daily/1633/pipeline
Job Page: https://ci.pingcap.net/blue/organizations/jenkins/tiflash_regression_test_daily

1. Minimal reproduce step (Required)

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

3. What did you see instead (Required)

[2022/03/15 15:42:59.955 +00:00] [ERROR] [MinTSOScheduler.cpp:150] ["MinTSOScheduler:threads are unavailable for the query 431845270763601921 (is min_tso 431845270763601921) when directly schedule it, need 23, but used 9997 of the thread hard limit 10000, 1 active and 0 waiting queries."] [thread_id=204]

4. What is your TiFlash version? (Required)

master