Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.2(EOL), 10.3(EOL), 10.4(EOL)
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None
Description
The documentation says that the thread_cache_size system variable supports auto-sizing in MariaDB 10.2 and later, and that auto-sizing is the default:
From MariaDB 10.2.0, the default is automatically set to the smaller of either 256, or the max_connections size.
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https://mariadb.com/kb/en/library/server-system-variables/#thread_cache_size
However, this does not seem to be the case. This system variable does not support AUTO_SET, and the default is 256:
static Sys_var_ulong Sys_thread_cache_size(
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"thread_cache_size",
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"How many threads we should keep in a cache for reuse. These are freed after 5 minutes of idle time",
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GLOBAL_VAR(thread_cache_size), CMD_LINE(REQUIRED_ARG),
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VALID_RANGE(0, 16384), DEFAULT(256), BLOCK_SIZE(1));
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https://github.com/MariaDB/server/blob/mariadb-10.4.6/sql/sys_vars.cc#L3655
The only time that this system variable appears to be auto-sized is if its configured value is greater than max_connections:
/* Ensure that some variables are not set higher than needed */
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if (thread_cache_size > max_connections)
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SYSVAR_AUTOSIZE(thread_cache_size, max_connections);
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https://github.com/MariaDB/server/blob/mariadb-10.4.6/sql/mysqld.cc#L9013
Is this a documentation bug, or is the behavior of thread_cache_size incorrect?
Attachments
Issue Links
- relates to
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MDEV-19839 refactor --autoset
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- Open
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- Open
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Activity
| Field | Original Value | New Value |
|---|---|---|
| Link | This issue relates to MDEV-19895 [ MDEV-19895 ] |
| Link | This issue relates to MDEV-19839 [ MDEV-19839 ] |
| Affects Version/s | 10.2.25 [ 23408 ] | |
| Affects Version/s | 10.3.16 [ 23410 ] | |
| Affects Version/s | 10.4.6 [ 23412 ] | |
| Issue Type | Bug [ 1 ] | Task [ 3 ] |
| Issue Type | Task [ 3 ] | Bug [ 1 ] |
| Affects Version/s | 10.2 [ 14601 ] | |
| Affects Version/s | 10.3 [ 22126 ] | |
| Affects Version/s | 10.4 [ 22408 ] |
| Summary | Support AUTO_SET for thread_cache_size system variable | --autoset-thread-cache-size doesn't work |
| Assignee | Sergei Golubchik [ serg ] | Ian Gilfillan [ greenman ] |
| Fix Version/s | N/A [ 14700 ] | |
| Fix Version/s | 10.2 [ 14601 ] | |
| Fix Version/s | 10.3 [ 22126 ] | |
| Fix Version/s | 10.4 [ 22408 ] |
| Resolution | Fixed [ 1 ] | |
| Status | Open [ 1 ] | Closed [ 6 ] |
| Workflow | MariaDB v3 [ 97824 ] | MariaDB v4 [ 156411 ] |
Looks like a documentation bug. It didn't do "smaller of either 256, or the max_connections size" even in 10.2.0