[Maria-discuss] Reason for changing the thread_pool_size default value?
Hi
What was the reason for changing the default thread_pool_size from the number of CPU's to 8?
If I look at the history of sql_vars.cc - https://github.com/MariaDB/server/commits/10.1/sql/sys_vars.cc?page=2 - the commit made on the 17th of November still has it as the number of CPU's, but the next commit on the 2nd of December has it at 8. This doesn't appear as a change in the summary.
ian
Hi, Ian!
On Mar 19, Ian Gilfillan wrote:
What was the reason for changing the default thread_pool_size from the number of CPU's to 8?
If I look at the history of sql_vars.cc - https://github.com/MariaDB/server/commits/10.1/sql/sys_vars.cc?page=2 - the commit made on the 17th of November still has it as the number of CPU's, but the next commit on the 2nd of December has it at 8. This doesn't appear as a change in the summary.
It was done by me with the comment "GLOBAL_VALUE_ORIGIN=AUTO" (which was one in the series of commits implementing SYSTEM_VARIABLES table).
The INFORMATION_SCHEMA.SYSTEM_VARIABLES table has a GLOBAL_VALUE_ORIGIN column that tell where the global value of the variable comes from.
"DEFAULT" means a compiled-in default, a constant, which is always the same for a given binary.
Using an expression as a default value for thread_pool_size didn't really fit that description. All default values must be constants.
So, I've moved this assignment to mysqld.cc - that is, thread_pool_size still gets the value from the number of CPU's. But by doing it, it sets the GLOBAL_VALUE_ORIGIN to AUTO (auto-sized), not DEFAULT.
Regards, Sergei
participants (2)
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Ian Gilfillan -
Sergei Golubchik