[MDEV-26440] Missing connection id value in I_S.thread_pool_queues - Jira

Details

Type: Bug
Status: Closed (View Workflow)
Priority: Major
Resolution: Fixed
Affects Version/s: 10.5.10, 10.5.11, 10.5.12
Fix Version/s: 10.5.13, 10.6.5
Component/s: Server
Labels:
None

Description

As far as I can tell, column I_S.thread_pool_queues.connection_id is supposed to contain ids of connections that are waiting for available worker threads.
The issue is that I haven't observed any values in this column besides NULL.
That makes it not quite possible to discern connections that are really sleeping from those that have queued queries.

Can be reproduced using official docker image.

MARIADB_VERSION=10.5.12 ./test-in-contaner.sh ./thread-pool-queues.sh > ./result.txt

Result:

cat result.txt

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        0 |          NULL |                      18301 |

|        0 |        1 |        0 |          NULL |                      16621 |

|        0 |        2 |        0 |          NULL |                      16214 |

|        0 |        3 |        0 |          NULL |                      15903 |

|        0 |        4 |        0 |          NULL |                      14968 |

|        0 |        5 |        0 |          NULL |                      14366 |

|        0 |        6 |        0 |          NULL |                      12835 |

|        0 |        7 |        0 |          NULL |                      11526 |

+----------+----------+----------+---------------+----------------------------+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        1 |          NULL |                      56000 |

|        0 |        1 |        1 |          NULL |                      56000 |

|        0 |        2 |        1 |          NULL |                      56000 |

|        0 |        3 |        1 |          NULL |                      56000 |

|        0 |        4 |        1 |          NULL |                      56000 |

|        0 |        5 |        1 |          NULL |                      56000 |

+----------+----------+----------+---------------+----------------------------+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        1 |          NULL |                    1068634 |

|        0 |        1 |        1 |          NULL |                    1068634 |

|        0 |        2 |        1 |          NULL |                    1068634 |

|        0 |        3 |        1 |          NULL |                    1068634 |

+----------+----------+----------+---------------+----------------------------+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        0 |          NULL |                    2081406 |

|        0 |        1 |        0 |          NULL |                    2081406 |

|        0 |        2 |        0 |          NULL |                    2081406 |

|        0 |        3 |        1 |          NULL |                     584074 |

|        0 |        4 |        1 |          NULL |                     584074 |

|        0 |        5 |        1 |          NULL |                     584074 |

|        0 |        6 |        1 |          NULL |                     466012 |

+----------+----------+----------+---------------+----------------------------+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        0 |          NULL |                    3093475 |

|        0 |        1 |        0 |          NULL |                    1596143 |

|        0 |        2 |        0 |          NULL |                    1596143 |

|        0 |        3 |        0 |          NULL |                    1596143 |

|        0 |        4 |        0 |          NULL |                    1478081 |

|        0 |        5 |        1 |          NULL |                     920131 |

|        0 |        6 |        1 |          NULL |                     460330 |

+----------+----------+----------+---------------+----------------------------+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        0 |          NULL |                    2608249 |

|        0 |        1 |        0 |          NULL |                    2608249 |

|        0 |        2 |        0 |          NULL |                    2490187 |

|        0 |        3 |        0 |          NULL |                    1932237 |

|        0 |        4 |        0 |          NULL |                    1472436 |

|        0 |        5 |        1 |          NULL |                     836087 |

|        0 |        6 |        1 |          NULL |                     345225 |

+----------+----------+----------+---------------+----------------------------+

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test-in-contaner.sh
1 kB
2021-08-19 09:09
thread-pool-queues.sh
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2021-08-19 09:09

Issue Links

relates to

MDEV-24757 Potential null pointer dereference in I_S.thread_pool_queues

Closed

Activity

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Vladislav Vaintroub added a comment - 2021-08-19 10:31 - edited

As far as I can tell, it will show you connection ids when those are available. If you get NULL, connection initialization (authentication and so on) did not yet succeed, and connection is not in the the list which is shown in "show processlist". Connections that are really sleeping are not part of any theadpool queues, but "show processlist", or corresponding information_schema.processlist table will show them with status Sleep , see e.g https://stackoverflow.com/q/12194241/547065

Vladislav Vaintroub added a comment - 2021-08-19 10:31 - edited As far as I can tell, it will show you connection ids when those are available. If you get NULL, connection initialization (authentication and so on) did not yet succeed, and connection is not in the the list which is shown in "show processlist". Connections that are really sleeping are not part of any theadpool queues, but "show processlist", or corresponding information_schema.processlist table will show them with status Sleep , see e.g https://stackoverflow.com/q/12194241/547065

Alex Sladkov added a comment - 2021-08-19 11:19 - edited

it will show you connection ids when those are available

I'm inclined to believe this is not always the case.

If we add output of show processlist to thread-pool-queues.sh script,

-while $MYSQL_VIA_EXTRA_PORT -e 'SELECT ID FROM INFORMATION_SCHEMA.PROCESSLIST WHERE ID != CONNECTION_ID()' | grep -q '.*' ; do

+while $MYSQL_VIA_EXTRA_PORT -t -e 'SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST WHERE ID != CONNECTION_ID()' | grep '.*' ; do

the result becomes like this

+----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| ID | USER | HOST            | DB   | COMMAND | TIME | STATE | INFO                    | TIME_MS | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY             | TID |

+----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

|  9 | root | 127.0.0.1:41848 | NULL | Sleep   |    0 |       | NULL                    |   6.918 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 195 |

|  8 | root | localhost:41846 | test | Query   |    0 | NULL  | CALL test.spin(1000000) |   6.622 |     0 |         0 |    0.000 |       75976 |           75976 |             0 |    21183 | CALL test.spin(1000000) | 179 |

|  7 | root | 127.0.0.1:41844 | NULL | Sleep   |    0 |       | NULL                    |   6.642 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 179 |

|  6 | root | 127.0.0.1:41842 | NULL | Sleep   |    0 |       | NULL                    |   8.175 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 179 |

|  5 | root | localhost:41840 | test | Query   |    0 | NULL  | CALL test.spin(1000000) |   6.898 |     0 |         0 |    0.000 |       75904 |           75904 |             0 |    21204 | CALL test.spin(1000000) | 195 |

+----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        0 |          NULL |                       5302 |

|        0 |        1 |        1 |          NULL |                      15970 |

|        0 |        2 |        1 |          NULL |                      10693 |

|        0 |        3 |        1 |          NULL |                       5545 |

|        0 |        4 |        1 |          NULL |                       4527 |

|        0 |        5 |        1 |          NULL |                       2721 |

|        0 |        6 |        1 |          NULL |                        438 |

+----------+----------+----------+---------------+----------------------------+

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| ID | USER | HOST            | DB   | COMMAND | TIME | STATE | INFO                    | TIME_MS  | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY             | TID |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| 15 | root | 127.0.0.1:41860 | NULL | Sleep   |    1 |       | NULL                    | 1010.088 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 14 | root | 127.0.0.1:41858 | NULL | Sleep   |    1 |       | NULL                    | 1011.533 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 13 | root | 127.0.0.1:41856 | NULL | Sleep   |    1 |       | NULL                    | 1013.235 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 12 | root | 127.0.0.1:41854 | NULL | Sleep   |    1 |       | NULL                    | 1016.408 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 10 | root | 127.0.0.1:41850 | NULL | Sleep   |    1 |       | NULL                    | 1017.544 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

|  9 | root | 127.0.0.1:41848 | NULL | Sleep   |    1 |       | NULL                    | 1028.052 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 195 |

|  8 | root | localhost:41846 | test | Query   |    1 | NULL  | CALL test.spin(1000000) | 1027.756 |     0 |         0 |    0.000 |       75976 |           75976 |             0 |  5237951 | CALL test.spin(1000000) | 179 |

|  7 | root | 127.0.0.1:41844 | NULL | Sleep   |    1 |       | NULL                    | 1027.776 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 179 |

|  6 | root | localhost:41842 | test | Query   |    1 | NULL  | CALL test.spin(1000000) | 1010.062 |     0 |         0 |    0.000 |       75976 |           75976 |             0 |  5237975 | CALL test.spin(1000000) | 196 |

|  5 | root | localhost:41840 | test | Query   |    1 | NULL  | CALL test.spin(1000000) | 1028.032 |     0 |         0 |    0.000 |       75904 |           75904 |             0 |  5237986 | CALL test.spin(1000000) | 195 |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        1 |          NULL |                    1050922 |

|        0 |        1 |        1 |          NULL |                    1045774 |

|        0 |        2 |        1 |          NULL |                    1044756 |

|        0 |        3 |        1 |          NULL |                    1042950 |

|        0 |        4 |        1 |          NULL |                    1040667 |

|        0 |        5 |        1 |          NULL |                    1039285 |

|        0 |        6 |        1 |          NULL |                    1038386 |

+----------+----------+----------+---------------+----------------------------+

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| ID | USER | HOST            | DB   | COMMAND | TIME | STATE | INFO                    | TIME_MS  | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY             | TID |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| 15 | root | 127.0.0.1:41860 | NULL | Sleep   |    2 |       | NULL                    | 2063.289 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 14 | root | 127.0.0.1:41858 | NULL | Sleep   |    2 |       | NULL                    | 2064.734 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 13 | root | 127.0.0.1:41856 | NULL | Sleep   |    2 |       | NULL                    | 2066.436 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 12 | root | localhost:41854 | test | Query   |    0 | NULL  | CALL test.spin(1000000) |  279.281 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 10522800 | CALL test.spin(1000000) | 195 |

| 10 | root | localhost:41850 | test | Query   |    0 | NULL  | CALL test.spin(1000000) |  297.449 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 10522813 | CALL test.spin(1000000) | 196 |

|  9 | root | localhost:41848 | test | Query   |    0 | NULL  | CALL test.spin(1000000) |  330.647 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 10522826 | CALL test.spin(1000000) | 179 |

|  8 | root | 127.0.0.1:41846 | NULL | Sleep   |    0 |       | NULL                    |  331.299 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |       50 | NULL                    | 179 |

|  7 | root | 127.0.0.1:41844 | NULL | Sleep   |    2 |       | NULL                    | 2080.977 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 179 |

|  6 | root | 127.0.0.1:41842 | NULL | Sleep   |    0 |       | NULL                    |  297.532 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |    54180 | NULL                    | 196 |

|  5 | root | 127.0.0.1:41840 | NULL | Sleep   |    0 |       | NULL                    |  279.339 |     0 |         0 |    0.000 |       74064 |           75904 |             0 |        5 | NULL                    | 195 |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        0 |          NULL |                    2080790 |

|        0 |        1 |        0 |          NULL |                    2078507 |

|        0 |        2 |        0 |          NULL |                    2077125 |

|        0 |        3 |        0 |          NULL |                    2076226 |

|        0 |        4 |        1 |          NULL |                     343666 |

|        0 |        5 |        1 |          NULL |                     309937 |

|        0 |        6 |        1 |          NULL |                     291611 |

+----------+----------+----------+---------------+----------------------------+

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| ID | USER | HOST            | DB   | COMMAND | TIME | STATE | INFO                    | TIME_MS  | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY             | TID |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| 15 | root | 127.0.0.1:41860 | NULL | Sleep   |    3 |       | NULL                    | 3083.463 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 14 | root | 127.0.0.1:41858 | NULL | Sleep   |    3 |       | NULL                    | 3084.908 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 13 | root | 127.0.0.1:41856 | NULL | Sleep   |    3 |       | NULL                    | 3086.610 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 12 | root | localhost:41854 | test | Query   |    1 | NULL  | CALL test.spin(1000000) | 1299.455 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 15765328 | CALL test.spin(1000000) | 195 |

| 10 | root | localhost:41850 | test | Query   |    1 | NULL  | CALL test.spin(1000000) | 1317.623 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 15765338 | CALL test.spin(1000000) | 196 |

|  9 | root | localhost:41848 | test | Query   |    1 | NULL  | CALL test.spin(1000000) | 1350.821 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 15765351 | CALL test.spin(1000000) | 179 |

|  8 | root | 127.0.0.1:41846 | NULL | Sleep   |    1 |       | NULL                    | 1351.473 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |       50 | NULL                    | 179 |

|  7 | root | 127.0.0.1:41844 | NULL | Sleep   |    3 |       | NULL                    | 3101.151 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 179 |

|  6 | root | 127.0.0.1:41842 | NULL | Sleep   |    1 |       | NULL                    | 1317.706 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |    54180 | NULL                    | 196 |

|  5 | root | 127.0.0.1:41840 | NULL | Sleep   |    1 |       | NULL                    | 1299.513 |     0 |         0 |    0.000 |       74064 |           75904 |             0 |        5 | NULL                    | 195 |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        0 |          NULL |                    3100883 |

|        0 |        1 |        0 |          NULL |                    3098600 |

|        0 |        2 |        0 |          NULL |                    3097218 |

|        0 |        3 |        0 |          NULL |                    3096319 |

|        0 |        4 |        0 |          NULL |                    1363759 |

|        0 |        5 |        1 |          NULL |                    1330030 |

|        0 |        6 |        1 |          NULL |                    1311704 |

+----------+----------+----------+---------------+----------------------------+

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| ID | USER | HOST            | DB   | COMMAND | TIME | STATE | INFO                    | TIME_MS  | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY             | TID |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| 15 | root | 127.0.0.1:41860 | NULL | Sleep   |    4 |       | NULL                    | 4117.876 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 14 | root | localhost:41858 | test | Query   |    0 | NULL  | CALL test.spin(1000000) |  576.792 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 21034487 | CALL test.spin(1000000) | 195 |

| 13 | root | localhost:41856 | test | Query   |    0 | NULL  | CALL test.spin(1000000) |  607.875 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 21034941 | CALL test.spin(1000000) | 196 |

| 12 | root | 127.0.0.1:41854 | NULL | Sleep   |    0 |       | NULL                    |  576.844 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |  9115891 | NULL                    | 195 |

| 10 | root | 127.0.0.1:41850 | NULL | Sleep   |    0 |       | NULL                    |  607.927 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |  9025917 | NULL                    | 196 |

|  9 | root | 127.0.0.1:41848 | NULL | Sleep   |    0 |       | NULL                    |  624.182 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |  8861726 | NULL                    | 179 |

|  8 | root | 127.0.0.1:41846 | NULL | Sleep   |    2 |       | NULL                    | 2385.886 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |       50 | NULL                    | 179 |

|  7 | root | localhost:41844 | test | Query   |    0 | NULL  | CALL test.spin(1000000) |  624.115 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 21028113 | CALL test.spin(1000000) | 179 |

|  6 | root | 127.0.0.1:41842 | NULL | Sleep   |    2 |       | NULL                    | 2352.119 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |    54180 | NULL                    | 196 |

|  5 | root | 127.0.0.1:41840 | NULL | Sleep   |    2 |       | NULL                    | 2333.926 |     0 |         0 |    0.000 |       74064 |           75904 |             0 |        5 | NULL                    | 195 |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        0 |          NULL |                    4131844 |

|        0 |        1 |        0 |          NULL |                    2399284 |

|        0 |        2 |        0 |          NULL |                    2365555 |

|        0 |        3 |        0 |          NULL |                    2347229 |

|        0 |        4 |        1 |          NULL |                     637590 |

|        0 |        5 |        1 |          NULL |                     621483 |

|        0 |        6 |        1 |          NULL |                     590380 |

+----------+----------+----------+---------------+----------------------------+

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| ID | USER | HOST            | DB   | COMMAND | TIME | STATE | INFO                    | TIME_MS  | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY             | TID |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| 15 | root | 127.0.0.1:41860 | NULL | Sleep   |    5 |       | NULL                    | 5145.195 |     0 |         0 |    0.000 |       74904 |           74904 |             0 |        0 | NULL                    | 196 |

| 14 | root | localhost:41858 | test | Query   |    1 | NULL  | CALL test.spin(1000000) | 1604.111 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 26326431 | CALL test.spin(1000000) | 195 |

| 13 | root | localhost:41856 | test | Query   |    1 | NULL  | CALL test.spin(1000000) | 1635.194 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 26326443 | CALL test.spin(1000000) | 196 |

| 12 | root | 127.0.0.1:41854 | NULL | Sleep   |    1 |       | NULL                    | 1604.163 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |  9115891 | NULL                    | 195 |

| 10 | root | 127.0.0.1:41850 | NULL | Sleep   |    1 |       | NULL                    | 1635.246 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |  9025917 | NULL                    | 196 |

|  9 | root | 127.0.0.1:41848 | NULL | Sleep   |    1 |       | NULL                    | 1651.501 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |  8861726 | NULL                    | 179 |

|  8 | root | 127.0.0.1:41846 | NULL | Sleep   |    3 |       | NULL                    | 3413.205 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |       50 | NULL                    | 179 |

|  7 | root | localhost:41844 | test | Query   |    1 | NULL  | CALL test.spin(1000000) | 1651.434 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 26326494 | CALL test.spin(1000000) | 179 |

|  6 | root | 127.0.0.1:41842 | NULL | Sleep   |    3 |       | NULL                    | 3379.438 |     0 |         0 |    0.000 |       74064 |           75976 |             0 |    54180 | NULL                    | 196 |

|  5 | root | 127.0.0.1:41840 | NULL | Sleep   |    3 |       | NULL                    | 3361.245 |     0 |         0 |    0.000 |       74064 |           75904 |             0 |        5 | NULL                    | 195 |

+----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        0 |          NULL |                    5157136 |

|        0 |        1 |        0 |          NULL |                    3424576 |

|        0 |        2 |        0 |          NULL |                    3390847 |

|        0 |        3 |        0 |          NULL |                    3372521 |

|        0 |        4 |        0 |          NULL |                    1662882 |

|        0 |        5 |        0 |          NULL |                    1646775 |

|        0 |        6 |        0 |          NULL |                    1615672 |

+----------+----------+----------+---------------+----------------------------+

+----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| ID | USER | HOST            | DB   | COMMAND | TIME | STATE | INFO                    | TIME_MS | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY             | TID |

+----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

| 15 | root | localhost:41860 | test | Query   |    0 | NULL  | CALL test.spin(1000000) | 920.890 |     0 |         0 |    0.000 |       75976 |           75976 |             0 | 28644753 | CALL test.spin(1000000) | 196 |

| 14 | root | 127.0.0.1:41858 | NULL | Sleep   |    0 |       | NULL                    | 825.878 |     0 |         0 |    0.000 |       74064 |           75976 |             0 | 18138272 | NULL                    | 195 |

+----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+

+----------+----------+----------+---------------+----------------------------+

| GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS |

+----------+----------+----------+---------------+----------------------------+

|        0 |        0 |        1 |          NULL |                     833917 |

+----------+----------+----------+---------------+----------------------------+

Here we can see that USER column is non-empty, so connection initialization has probably completed, and also we can see very suspicious correlation between INFORMATION_SCHEMA.PROCESSLIST.TIME_MS and INFORMATION_SCHEMA.THREAD_POOL_QUEUES.QUEUEING_TIME_MICROSECONDS values.
Because of that I think that these connections are in fact already in queue for query execution, but CONNECTION_ID for some reason is still showing NULL.

Alex Sladkov added a comment - 2021-08-19 11:19 - edited it will show you connection ids when those are available I'm inclined to believe this is not always the case. If we add output of show processlist to thread-pool-queues.sh script, -while $MYSQL_VIA_EXTRA_PORT -e 'SELECT ID FROM INFORMATION_SCHEMA.PROCESSLIST WHERE ID != CONNECTION_ID()' | grep -q '.*' ; do +while $MYSQL_VIA_EXTRA_PORT -t -e 'SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST WHERE ID != CONNECTION_ID()' | grep '.*' ; do the result becomes like this +----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | TIME_MS | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY | TID | +----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | 9 | root | 127.0.0.1:41848 | NULL | Sleep | 0 | | NULL | 6.918 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 195 | | 8 | root | localhost:41846 | test | Query | 0 | NULL | CALL test.spin(1000000) | 6.622 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 21183 | CALL test.spin(1000000) | 179 | | 7 | root | 127.0.0.1:41844 | NULL | Sleep | 0 | | NULL | 6.642 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 179 | | 6 | root | 127.0.0.1:41842 | NULL | Sleep | 0 | | NULL | 8.175 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 179 | | 5 | root | localhost:41840 | test | Query | 0 | NULL | CALL test.spin(1000000) | 6.898 | 0 | 0 | 0.000 | 75904 | 75904 | 0 | 21204 | CALL test.spin(1000000) | 195 | +----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ +----------+----------+----------+---------------+----------------------------+ | GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS | +----------+----------+----------+---------------+----------------------------+ | 0 | 0 | 0 | NULL | 5302 | | 0 | 1 | 1 | NULL | 15970 | | 0 | 2 | 1 | NULL | 10693 | | 0 | 3 | 1 | NULL | 5545 | | 0 | 4 | 1 | NULL | 4527 | | 0 | 5 | 1 | NULL | 2721 | | 0 | 6 | 1 | NULL | 438 | +----------+----------+----------+---------------+----------------------------+ +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | TIME_MS | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY | TID | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | 15 | root | 127.0.0.1:41860 | NULL | Sleep | 1 | | NULL | 1010.088 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 14 | root | 127.0.0.1:41858 | NULL | Sleep | 1 | | NULL | 1011.533 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 13 | root | 127.0.0.1:41856 | NULL | Sleep | 1 | | NULL | 1013.235 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 12 | root | 127.0.0.1:41854 | NULL | Sleep | 1 | | NULL | 1016.408 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 10 | root | 127.0.0.1:41850 | NULL | Sleep | 1 | | NULL | 1017.544 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 9 | root | 127.0.0.1:41848 | NULL | Sleep | 1 | | NULL | 1028.052 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 195 | | 8 | root | localhost:41846 | test | Query | 1 | NULL | CALL test.spin(1000000) | 1027.756 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 5237951 | CALL test.spin(1000000) | 179 | | 7 | root | 127.0.0.1:41844 | NULL | Sleep | 1 | | NULL | 1027.776 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 179 | | 6 | root | localhost:41842 | test | Query | 1 | NULL | CALL test.spin(1000000) | 1010.062 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 5237975 | CALL test.spin(1000000) | 196 | | 5 | root | localhost:41840 | test | Query | 1 | NULL | CALL test.spin(1000000) | 1028.032 | 0 | 0 | 0.000 | 75904 | 75904 | 0 | 5237986 | CALL test.spin(1000000) | 195 | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ +----------+----------+----------+---------------+----------------------------+ | GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS | +----------+----------+----------+---------------+----------------------------+ | 0 | 0 | 1 | NULL | 1050922 | | 0 | 1 | 1 | NULL | 1045774 | | 0 | 2 | 1 | NULL | 1044756 | | 0 | 3 | 1 | NULL | 1042950 | | 0 | 4 | 1 | NULL | 1040667 | | 0 | 5 | 1 | NULL | 1039285 | | 0 | 6 | 1 | NULL | 1038386 | +----------+----------+----------+---------------+----------------------------+ +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | TIME_MS | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY | TID | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | 15 | root | 127.0.0.1:41860 | NULL | Sleep | 2 | | NULL | 2063.289 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 14 | root | 127.0.0.1:41858 | NULL | Sleep | 2 | | NULL | 2064.734 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 13 | root | 127.0.0.1:41856 | NULL | Sleep | 2 | | NULL | 2066.436 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 12 | root | localhost:41854 | test | Query | 0 | NULL | CALL test.spin(1000000) | 279.281 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 10522800 | CALL test.spin(1000000) | 195 | | 10 | root | localhost:41850 | test | Query | 0 | NULL | CALL test.spin(1000000) | 297.449 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 10522813 | CALL test.spin(1000000) | 196 | | 9 | root | localhost:41848 | test | Query | 0 | NULL | CALL test.spin(1000000) | 330.647 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 10522826 | CALL test.spin(1000000) | 179 | | 8 | root | 127.0.0.1:41846 | NULL | Sleep | 0 | | NULL | 331.299 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 50 | NULL | 179 | | 7 | root | 127.0.0.1:41844 | NULL | Sleep | 2 | | NULL | 2080.977 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 179 | | 6 | root | 127.0.0.1:41842 | NULL | Sleep | 0 | | NULL | 297.532 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 54180 | NULL | 196 | | 5 | root | 127.0.0.1:41840 | NULL | Sleep | 0 | | NULL | 279.339 | 0 | 0 | 0.000 | 74064 | 75904 | 0 | 5 | NULL | 195 | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ +----------+----------+----------+---------------+----------------------------+ | GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS | +----------+----------+----------+---------------+----------------------------+ | 0 | 0 | 0 | NULL | 2080790 | | 0 | 1 | 0 | NULL | 2078507 | | 0 | 2 | 0 | NULL | 2077125 | | 0 | 3 | 0 | NULL | 2076226 | | 0 | 4 | 1 | NULL | 343666 | | 0 | 5 | 1 | NULL | 309937 | | 0 | 6 | 1 | NULL | 291611 | +----------+----------+----------+---------------+----------------------------+ +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | TIME_MS | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY | TID | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | 15 | root | 127.0.0.1:41860 | NULL | Sleep | 3 | | NULL | 3083.463 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 14 | root | 127.0.0.1:41858 | NULL | Sleep | 3 | | NULL | 3084.908 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 13 | root | 127.0.0.1:41856 | NULL | Sleep | 3 | | NULL | 3086.610 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 12 | root | localhost:41854 | test | Query | 1 | NULL | CALL test.spin(1000000) | 1299.455 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 15765328 | CALL test.spin(1000000) | 195 | | 10 | root | localhost:41850 | test | Query | 1 | NULL | CALL test.spin(1000000) | 1317.623 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 15765338 | CALL test.spin(1000000) | 196 | | 9 | root | localhost:41848 | test | Query | 1 | NULL | CALL test.spin(1000000) | 1350.821 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 15765351 | CALL test.spin(1000000) | 179 | | 8 | root | 127.0.0.1:41846 | NULL | Sleep | 1 | | NULL | 1351.473 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 50 | NULL | 179 | | 7 | root | 127.0.0.1:41844 | NULL | Sleep | 3 | | NULL | 3101.151 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 179 | | 6 | root | 127.0.0.1:41842 | NULL | Sleep | 1 | | NULL | 1317.706 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 54180 | NULL | 196 | | 5 | root | 127.0.0.1:41840 | NULL | Sleep | 1 | | NULL | 1299.513 | 0 | 0 | 0.000 | 74064 | 75904 | 0 | 5 | NULL | 195 | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ +----------+----------+----------+---------------+----------------------------+ | GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS | +----------+----------+----------+---------------+----------------------------+ | 0 | 0 | 0 | NULL | 3100883 | | 0 | 1 | 0 | NULL | 3098600 | | 0 | 2 | 0 | NULL | 3097218 | | 0 | 3 | 0 | NULL | 3096319 | | 0 | 4 | 0 | NULL | 1363759 | | 0 | 5 | 1 | NULL | 1330030 | | 0 | 6 | 1 | NULL | 1311704 | +----------+----------+----------+---------------+----------------------------+ +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | TIME_MS | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY | TID | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | 15 | root | 127.0.0.1:41860 | NULL | Sleep | 4 | | NULL | 4117.876 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 14 | root | localhost:41858 | test | Query | 0 | NULL | CALL test.spin(1000000) | 576.792 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 21034487 | CALL test.spin(1000000) | 195 | | 13 | root | localhost:41856 | test | Query | 0 | NULL | CALL test.spin(1000000) | 607.875 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 21034941 | CALL test.spin(1000000) | 196 | | 12 | root | 127.0.0.1:41854 | NULL | Sleep | 0 | | NULL | 576.844 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 9115891 | NULL | 195 | | 10 | root | 127.0.0.1:41850 | NULL | Sleep | 0 | | NULL | 607.927 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 9025917 | NULL | 196 | | 9 | root | 127.0.0.1:41848 | NULL | Sleep | 0 | | NULL | 624.182 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 8861726 | NULL | 179 | | 8 | root | 127.0.0.1:41846 | NULL | Sleep | 2 | | NULL | 2385.886 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 50 | NULL | 179 | | 7 | root | localhost:41844 | test | Query | 0 | NULL | CALL test.spin(1000000) | 624.115 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 21028113 | CALL test.spin(1000000) | 179 | | 6 | root | 127.0.0.1:41842 | NULL | Sleep | 2 | | NULL | 2352.119 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 54180 | NULL | 196 | | 5 | root | 127.0.0.1:41840 | NULL | Sleep | 2 | | NULL | 2333.926 | 0 | 0 | 0.000 | 74064 | 75904 | 0 | 5 | NULL | 195 | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ +----------+----------+----------+---------------+----------------------------+ | GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS | +----------+----------+----------+---------------+----------------------------+ | 0 | 0 | 0 | NULL | 4131844 | | 0 | 1 | 0 | NULL | 2399284 | | 0 | 2 | 0 | NULL | 2365555 | | 0 | 3 | 0 | NULL | 2347229 | | 0 | 4 | 1 | NULL | 637590 | | 0 | 5 | 1 | NULL | 621483 | | 0 | 6 | 1 | NULL | 590380 | +----------+----------+----------+---------------+----------------------------+ +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | TIME_MS | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY | TID | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | 15 | root | 127.0.0.1:41860 | NULL | Sleep | 5 | | NULL | 5145.195 | 0 | 0 | 0.000 | 74904 | 74904 | 0 | 0 | NULL | 196 | | 14 | root | localhost:41858 | test | Query | 1 | NULL | CALL test.spin(1000000) | 1604.111 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 26326431 | CALL test.spin(1000000) | 195 | | 13 | root | localhost:41856 | test | Query | 1 | NULL | CALL test.spin(1000000) | 1635.194 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 26326443 | CALL test.spin(1000000) | 196 | | 12 | root | 127.0.0.1:41854 | NULL | Sleep | 1 | | NULL | 1604.163 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 9115891 | NULL | 195 | | 10 | root | 127.0.0.1:41850 | NULL | Sleep | 1 | | NULL | 1635.246 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 9025917 | NULL | 196 | | 9 | root | 127.0.0.1:41848 | NULL | Sleep | 1 | | NULL | 1651.501 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 8861726 | NULL | 179 | | 8 | root | 127.0.0.1:41846 | NULL | Sleep | 3 | | NULL | 3413.205 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 50 | NULL | 179 | | 7 | root | localhost:41844 | test | Query | 1 | NULL | CALL test.spin(1000000) | 1651.434 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 26326494 | CALL test.spin(1000000) | 179 | | 6 | root | 127.0.0.1:41842 | NULL | Sleep | 3 | | NULL | 3379.438 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 54180 | NULL | 196 | | 5 | root | 127.0.0.1:41840 | NULL | Sleep | 3 | | NULL | 3361.245 | 0 | 0 | 0.000 | 74064 | 75904 | 0 | 5 | NULL | 195 | +----+------+-----------------+------+---------+------+-------+-------------------------+----------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ +----------+----------+----------+---------------+----------------------------+ | GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS | +----------+----------+----------+---------------+----------------------------+ | 0 | 0 | 0 | NULL | 5157136 | | 0 | 1 | 0 | NULL | 3424576 | | 0 | 2 | 0 | NULL | 3390847 | | 0 | 3 | 0 | NULL | 3372521 | | 0 | 4 | 0 | NULL | 1662882 | | 0 | 5 | 0 | NULL | 1646775 | | 0 | 6 | 0 | NULL | 1615672 | +----------+----------+----------+---------------+----------------------------+ +----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | TIME_MS | STAGE | MAX_STAGE | PROGRESS | MEMORY_USED | MAX_MEMORY_USED | EXAMINED_ROWS | QUERY_ID | INFO_BINARY | TID | +----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ | 15 | root | localhost:41860 | test | Query | 0 | NULL | CALL test.spin(1000000) | 920.890 | 0 | 0 | 0.000 | 75976 | 75976 | 0 | 28644753 | CALL test.spin(1000000) | 196 | | 14 | root | 127.0.0.1:41858 | NULL | Sleep | 0 | | NULL | 825.878 | 0 | 0 | 0.000 | 74064 | 75976 | 0 | 18138272 | NULL | 195 | +----+------+-----------------+------+---------+------+-------+-------------------------+---------+-------+-----------+----------+-------------+-----------------+---------------+----------+-------------------------+-----+ +----------+----------+----------+---------------+----------------------------+ | GROUP_ID | POSITION | PRIORITY | CONNECTION_ID | QUEUEING_TIME_MICROSECONDS | +----------+----------+----------+---------------+----------------------------+ | 0 | 0 | 1 | NULL | 833917 | +----------+----------+----------+---------------+----------------------------+ Here we can see that USER column is non-empty, so connection initialization has probably completed, and also we can see very suspicious correlation between INFORMATION_SCHEMA.PROCESSLIST.TIME_MS and INFORMATION_SCHEMA.THREAD_POOL_QUEUES.QUEUEING_TIME_MICROSECONDS values. Because of that I think that these connections are in fact already in queue for query execution, but CONNECTION_ID for some reason is still showing NULL.

Vladislav Vaintroub added a comment - 2021-08-19 15:47 - edited

After some debugging, yes you're right, there is a bug in there.

Althought I'm still not getting your example, it uses the command line client to connect, execute a single query then disconnect.

A better example would need all clients to connect, then simultaneously execute some long query, then disconnect.
I'll try to come up with multithreading test, using more standard techniques, i.e mysql-test-run
and long SELECT SLEEP() queries to emulate blocking

Vladislav Vaintroub added a comment - 2021-08-19 15:47 - edited After some debugging, yes you're right, there is a bug in there. Althought I'm still not getting your example, it uses the command line client to connect, execute a single query then disconnect. A better example would need all clients to connect, then simultaneously execute some long query, then disconnect. I'll try to come up with multithreading test, using more standard techniques, i.e mysql-test-run and long SELECT SLEEP() queries to emulate blocking

Alex Sladkov added a comment - 2021-08-19 17:24

Althought I'm still not getting your example, it uses the command line client to connect, execute a single query then disconnect.

A better example would need all clients to connect, then simultaneously execute some long query, then disconnect.

My example in fact does run the long commands in parallel.
It would be certainly better to do as you suggest, but it's a bit tricky to do in a simple shell script, and I wasn't aware that mysql-test-run exists (by the way, thank you for teaching me about that!).
Also, I wasn't sure if SELECT SLEEP() actually blocks its thread, so I wrote that clumsy procedure to emulate blocking, but apparently it wasn't necessary.

Alex Sladkov added a comment - 2021-08-19 17:24 Althought I'm still not getting your example, it uses the command line client to connect, execute a single query then disconnect. A better example would need all clients to connect, then simultaneously execute some long query, then disconnect. My example in fact does run the long commands in parallel. It would be certainly better to do as you suggest, but it's a bit tricky to do in a simple shell script, and I wasn't aware that mysql-test-run exists (by the way, thank you for teaching me about that!). Also, I wasn't sure if SELECT SLEEP() actually blocks its thread, so I wrote that clumsy procedure to emulate blocking, but apparently it wasn't necessary.

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Assignee:: Vladislav Vaintroub

Reporter:: Alex Sladkov

Votes:: 0 Vote for this issue

Watchers:: 2 Start watching this issue

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Created:: 2021-08-19 09:09

Updated:: 2021-08-19 20:05

Resolved:: 2021-08-19 20:05

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