The query may hang in IndexMerge executor when it's killed

[xzhangxian1008]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

CREATE TABLE reproduce (
    c1 int primary key,
    c2 int,
    c3 int,
    key ci2(c2),
    key ci3(c3)
);

2. insert lots of rows about 100 million
3. select * from reproduce where c1 in (0, 10, 20, 30, ...., 10000) or c2 in (0, 10, 20, 30, ...., 10000) // make this query run for a long time
4. kill the query executed in step 3

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

Query should be successfully killed

3. What did you see instead (Required)

Query hang can not be successfully killed.

4. What is your TiDB version? (Required)

Commit Hash: dd60929

[guo-shaoge]

ignore some DMR(5.3, 6.3, 6.3)

[xzhangxian1008]

/open