Unable to timely kill OOM during mergeglobalstatus

[hawkingrei]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

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

can be killed in time.

3. What did you see instead (Required)

cannot be killed and report failed to kill.

4. What is your TiDB version? (Required)