Description:
The log thread is useless, but still running.
How to repeat:
1. show engine innodb status\G, some of the results are as follows, the log thread is running:
--------
FILE I/O
--------
I/O thread 0 state: waiting for completed aio requests (insert buffer thread)
I/O thread 1 state: waiting for completed aio requests (log thread)
I/O thread 2 state: waiting for completed aio requests (read thread)
I/O thread 3 state: waiting for completed aio requests (read thread)
I/O thread 4 state: waiting for completed aio requests (read thread)
I/O thread 5 state: waiting for completed aio requests (read thread)
I/O thread 6 state: waiting for completed aio requests (write thread)
I/O thread 7 state: waiting for completed aio requests (write thread)
I/O thread 8 state: waiting for completed aio requests (write thread)
I/O thread 9 state: waiting for completed aio requests (write thread)
2. From the source code, we find that in select_slot_array function, only s_reads\s_writes\s_ibuf are used for AIO.
No AIO requests will be submitted to the log thread. The log thread is used to write checkpoint information before, but the log_checkpointer thread is now responsible for this
Suggested fix:
Remove the log thread.
