Simplify SHOW THREADS columns

[sanikolaev]

As discussed in Slack, let's simplify and make less confusing the SHOW THREADS column names:

• Time/Work time => Thread uptime - thread uptime with no conditions.
• Time/Work time => Current job duration - how long the current job has been running. When the thread is idling - -.
• Last job took => Previous job duration - how long the previous job took. When there was no previous job - -.
• In idle: No (working) -> Thread status: working, idling

[sanikolaev]

As discussed on a call with Alexey, the specifics is that once a thread starts a new job we do not have access to the information about the previous job. It's only available if the thread is idling after processing a job. The thread uptime is mostly useful for VIP threads, for others it should be equal to the instance uptime. Provided that, the updated proposal is:

• Time => remove as it's mostly not needed
• Work time => This/prev job time, s:
  • when the thread is busy - how long the current job has been running, in seconds
  • when the thread is idling - previous job duration + suffix (prev)
• In idle: No (working) -> Thread status: working, idling

A few more simplification ideas:

• Tid => just ID to be consistent with ConnID in terms of letter capitalization and provided the command is called show threads just ID makes sense.
• Host => Connection from, so it's clear what "host" is meant. The longer column name makes sense, since it's mostly not longer than the values anyway

Examples

Now:

+----------+--------+-------+-------+-----------------+--------+----------+-----------+-----------+---------------+--------------+--------------+
| Tid      | Name   | Proto | State | Host            | ConnID | Time     | Work time | Jobs done | Last job took | In idle      | Info         |
+----------+--------+-------+-------+-----------------+--------+----------+-----------+-----------+---------------+--------------+--------------+
| 12074427 | work_5 | mysql | query | 127.0.0.1:60975 |   2114 | 0.000571 | 17s       |     83567 | 577us         | No (working) | show threads |
| 12074428 | work_6 |       | -     |                 |     -1 | 23.03297 | 16s       |     85689 | 148us         | 374ms ago    |              |                                            |
+----------+--------+-------+-------+-----------------+--------+----------+-----------+-----------+---------------+--------------+--------------+
1 row in set (0.04 sec)

Suggested:

+----------+--------+-------+-------+-----------------+--------+-----------------------+-----------+---------------+---------------+
| ID       | Name   | Proto | State | Connection from | ConnID | This/prev job time, s | Jobs done | Thread status | Info          |
+----------+--------+-------+-------+-----------------+--------+-----------------------+-----------+---------------+---------------+
| 12074427 | work_5 | mysql | query | 127.0.0.1:60975 |   2114 | 0.000571              |     83567 | working       | show threads  |
| 12074428 | work_6 |       | -     |                 |     -1 | 0.000148 (prev)       |     85689 | idling, 1s    |               |
+----------+--------+-------+-------+-----------------+--------+-----------------------+-----------+---------------+---------------+
2 rows in set (0.04 sec)

[githubmanticore]

➤ Aleksey N. Vinogradov commented:

suffix '(prev)' will make this column string-typed.
That is no difference for human, but will make parsing of such column significantly more complex.

[githubmanticore]

➤ Aleksey N. Vinogradov commented:

Also, 'Time' column is quite useful when also cpustat is in game. Then you will see also cpu time, and thread efficiency columns.

They were all on the screen, but was hidden as 'useless'. Now (without them) simple 'Time' also looks 'useless', but on removing, cpu time and thread efficiency will also became 'useless'.
'Tid' is namely thread id, it reflects the tid in process explorer, and may be used to manipulate a thread from global OS context. Simple 'ID' doesn't have such sense; we can just assign any values starting from 1.
For me, looking for 'tid' or 'threadID' is immediately clue to the ps output. And also, in logs and crash dumps the very same tid is in game. Just 'ID' is much harder. You need to KNOW that is not a random ID, but very same ThreadID, or tid.

[sanikolaev]

suffix '(prev)' will make this column string-typed.
That is no difference for human, but will make parsing of such column significantly more complex.

I think this is a reasonable tradeoff.

'Tid' is namely thread id, it reflects the tid in process explorer...

Good point! Let it be TID then like in man proc: "Each child task is represented by its TID."

Also, 'Time' column is quite useful when also cpustat is in game

Right. I forgot about it. I suggest to rename Thd efficiency to CPU activity which should suffice since the absolute CPU time is not so interesting. CPU activity also makes it clear that it's about CPU, not something else.

So the corrected list of suggested actions is:

• Time => remove
• Work time => This/prev job time, s:
  • when the thread is busy - how long the current job has been running, in seconds
  • when the thread is idling - previous job duration + suffix (prev)
• In idle: No (working) -> Thread status: working, idling
• Tid => TID
• Host => Connection from
• Work time CPU => remove
• Thd efficiency => CPU activity

[sanikolaev]

@PavelShilin89 please test that the change has been made as specified and update the docs if required (make a PR).

[PavelShilin89]

CLT tests done in #1509

[sanikolaev]

All done.