"select * from information_schema.tidb_trx" error

[tiancaiamao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

In a 1M tables environment, I run two mysql clients.

MySQL1:

mysql> select count(tidb_table_id) from information_schema.tables;
ERROR 8175 (HY000): Your query has been cancelled due to exceeding the allowed memory limit for a single SQL query. P
lease try narrowing your query scope or increase the tidb_mem_quota_query limit and try again.[conn=920649734]
mysql> 

During the execution of this query, execute "select * from information_schema.tidb_trx" several times.

MySQL2:

mysql> select * from tidb_trx;
ERROR 1105 (HY000): transaction future is not set
mysql> select * from tidb_trx;
^[[A+--------------------+----------------------------+--------------------+-------------------------+-------+------
--------------+-----------------+------------------+------------+------+--------------------+-----------------------
-----------------------------------------------+-------------------+--------------+
| ID                 | START_TIME                 | CURRENT_SQL_DIGEST | CURRENT_SQL_DIGEST_TEXT | STATE | WAITING_S
TART_TIME | MEM_BUFFER_KEYS | MEM_BUFFER_BYTES | SESSION_ID | USER | DB                 | ALL_SQL_DIGESTS           
                                           | RELATED_TABLE_IDS | WAITING_TIME |
+--------------------+----------------------------+--------------------+-------------------------+-------+----------
----------+-----------------+------------------+------------+------+--------------------+---------------------------
-------------------------------------------+-------------------+--------------+
| 454351137991819275 | 2024-12-03 15:47:23.731000 | NULL               | NULL                    | Idle  | NULL     
          |               0 |                0 |  920649734 | root |                    | ["a78636cadcc28711c100b1bd
9ef4ba6e9d7bb5dd5fc7cd7a1e3d21d44b11c824"] |                   |         NULL |
| 454351139630219265 | 2024-12-03 15:47:29.981000 | NULL               | NULL                    | Idle  | NULL     
          |               0 |                0 |  920649736 | root | information_schema | ["0cc25a9680ab3ad417f220fc
5500d21c46e5b1bc2630fb10eb3ada50b5c9b844"] |                   |         NULL |
+--------------------+----------------------------+--------------------+-------------------------+-------+----------
----------+-----------------+------------------+------------+------+--------------------+---------------------------
-------------------------------------------+-------------------+--------------+
2 rows in set (0.80 sec)

mysql> select * from tidb_trx;
ERROR 1105 (HY000): transaction future is not set
mysql> select * from tidb_trx;
ERROR 1105 (HY000): runtime error: invalid memory address or nil pointer dereference

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

No error such as "ERROR 1105 (HY000): transaction future is not set"
No error such as "ERROR 1105 (HY000): runtime error: invalid memory address or nil pointer dereference"

3. What did you see instead (Required)

error

4. What is your TiDB version? (Required)

master 5598c11

[tiancaiamao]

During I test #57937, I found the query on information_schema.tidb_trx is not expected.

[tiancaiamao]

Cannot reproduce it.
It seems to by caused by my changes in #57937