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Update MaxAdmin documentation

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'show threads' documentation was completely out of date.
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Johan Wikman
2018-10-08 15:18:26 +03:00
parent c7f07ec6b1
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Documentation/Reference/MaxAdmin.md
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@ -1172,34 +1172,43 @@ resource internally and are used to allow the tuning process to take place.
MariaDB MaxScale uses a number of threads, as defined in the MariaDB MaxScale
configuration file, to execute the processing of requests received from clients
and the handling of responses. The _show threads_ command can be used to
determine what each thread is currently being used for.
and the handling of responses.
The _show threads_ command can be used to determine how many descriptors the
threads are currently handling and how many descriptors the threads have handled
in total during the life-time of MaxScale, and the current and historical load
of the threads.
```
MaxScale> show threads
Polling Threads.
Historic Thread Load Average: 1.06.
Current Thread Load Average: 0.00.
15 Minute Average: 0.10, 5 Minute Average: 0.30, 1 Minute Average: 0.67
Pending event queue length averages:
15 Minute Average: 0.00, 5 Minute Average: 0.00, 1 Minute Average: 0.00
ID | State | # fds | Descriptor | Running | Event
----+------------+--------+------------------+----------+---------------
0 | Polling | | | |
1 | Polling | | | |
2 | Processing | 1 | 0x6e0dd0 | <202400ms | IN|OUT
3 | Polling | | | |
MaxScale>
ID | State | #descriptors (curr) | #descriptors (tot) | Load (1s) | Load (1m) | Load (1h) |
----+------------+---------------------+---------------------+-----------+-----------+-----------+
0 | Processing | 3 | 3 | 0 | 0 | 0 |
1 | Polling | 2 | 2 | 0 | 0 | 0 |
2 | Polling | 2 | 2 | 0 | 0 | 0 |
3 | Polling | 2 | 2 | 0 | 0 | 0 |
```
Note that as a client session may consist of one client descriptor and
several server descriptors, it is not possible to deduce the number of
client sessions from the descriptor count alone. If MaxScale is running ok,
the number of current and total descriptors should be roughly the same for
all threads.
The resultant output returns data as to the average thread utilization for the
past minutes 5 minutes and 15 minutes. It also gives a table, with a row per
thread that shows what DCB that thread is currently processing events for, the
events it is processing and how long, to the nearest 100ms has been send
processing these events.
The `Load (1s)` column shows the load during the last measured second, an
operation which is performed once per second. That is, the displayed value
shows the load for the second that ended 0 - 1 seconds before the
`show threads` command was issued.
The load during the measured second is defined as
`100 * (1 - time-spent-blocked-in-epoll_wait() / 1)` which translates into
a load of `0` if the thread is blocked in `epoll_wait()` for the entire
second, waiting for events to process, and `100` if the thread spends no time
blocked in `epoll_wait()` but processing events for the entire duration.
The `Load (1m)` value is the moving average of the last 60 second load values
and the `Load (1h)` value is the moving average of the last 60 minute load
values.
## The Housekeeper Tasks