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PS-10357 [Docs] - fix threadpool errors 8.0 #618

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patrickbirch merged 1 commit into from
Dec 4, 2025
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PS-10357 [Docs] - fix threadpool errors 8.0 #618

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38 changes: 16 additions & 22 deletions docs/threadpool.md
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Expand Up @@ -148,11 +148,7 @@ Administrators can fine-tune thread pool behavior by adjusting dynamic and stati
thread_pool_stall_limit = 100
```

```mysql
mysql> SET GLOBAL thread_pool_stall_limit = 100;
```

This value, in milliseconds, limits how long a task can stall before being redistributed. As with other thread pool settings, existing sessions retain their previous values.
This value, in milliseconds, limits how long a task can stall before being redistributed. This setting requires a server restart to take effect.


## Thread Pool Configuration Reference Sheet
Expand Down Expand Up @@ -182,7 +178,7 @@ A quick overview of system variables available for configuring the thread pool i
</tr>
<tr>
<td><code><a href="#thread_pool_size">thread_pool_size</a></code></td>
<td><code>16</code></td>
<td><code>Number of CPU cores</code></td>
<td>Global</td>
<td>No</td>
<td>Yes</td>
Expand Down Expand Up @@ -246,17 +242,17 @@ A quick overview of system variables available for configuring the thread pool i
<tbody>
<tr>
<td><code><a href="#thread_pool_max_threads">thread_pool_max_threads</a></code></td>
<td><code>1000</code></td>
<td><code>100000</code></td>
<td>Global</td>
<td>No</td>
<td>Yes</td>
<td>Maximum number of worker threads per group.</td>
<td>Yes</td>
<td>Maximum number of worker threads across all thread groups.</td>
</tr>
<tr>
<td><code><a href="#thread_pool_stall_limit">thread_pool_stall_limit</a></code></td>
<td><code>6</code></td>
<td><code>500</code></td>
<td>Global</td>
<td>Yes</td>
<td>No</td>
<td>Yes</td>
<td>Wait time in milliseconds before reassigning stalled queries.</td>
</tr>
Expand Down Expand Up @@ -374,7 +370,7 @@ Defines the number of thread groups.
* Description: Each group manages client connections with its own listener and
worker threads.

* Default: 16
* Default: Number of CPU cores detected on the system at server startup

* This value is static and requires a server restart.

Expand Down Expand Up @@ -427,28 +423,26 @@ Controls how long to wait before rescheduling stalled queries.
* Description: If a query remains blocked beyond this time, the pool may redistribute
it to another group.

* Default: 6

* This setting can be configured statically.
* Default: 500

* This setting can be configured dynamically.
* This setting is not dynamic and requires a server restart.

* This setting helps improve query responsiveness under unbalanced workloads.


### `thread_pool_max_threads`

Defines the maximum number of worker threads per group.
Defines the maximum number of worker threads across all thread groups combined.

* Allowed values: Integer ≥ `thread_pool_max_threads`
* Allowed values: Integer ≥ 1

* Description: Controls the upper bound on thread creation. If reached, new queries wait
in the queue.
* Description: Controls the upper bound on total thread creation across all thread groups. If reached, new queries wait in the queue.

* Default: 1000
* Default: 100000

* This setting is not dynamic and requires a server restart.
* This setting can be configured in the configuration file or changed dynamically at runtime using `SET GLOBAL`.

**Note:** The default value of 100000 is the maximum total number of worker threads across all thread groups. Consider setting a lower value based on your system's capacity and workload requirements to avoid resource exhaustion.


Use these variables together to tune concurrency, queue behavior, and scheduling
Expand Down
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