| Bug #78894 | buf_pool_resize can lock less in checking whether AHI is on or off | ||
|---|---|---|---|
| Submitted: | 21 Oct 2015 7:07 | Modified: | 21 Oct 2015 9:07 |
| Reporter: | Laurynas Biveinis (OCA) | Email Updates: | |
| Status: | Verified | Impact on me: | |
| Category: | MySQL Server: InnoDB storage engine | Severity: | S5 (Performance) |
| Version: | 5.7.8 | OS: | Any |
| Assigned to: | CPU Architecture: | Any | |
| Tags: | ahi, buffer pool resize, innodb | ||
[21 Oct 2015 9:07]
MySQL Verification Team
Hello Laurynas, Thank you for the report. Thanks, Umesh
Description: void buf_pool_resize() { ... btr_search_s_lock_all(); if (btr_search_enabled) { btr_search_s_unlock_all(); btr_search_disabled = true; } else { btr_search_s_unlock_all(); } ... So, it S-latches all the partitions to read btr_search_enabled. But btr_search_enable/disable X-latches all the partitions to change its value. So here it is not required to latch all the partitions, any single one of them is enough. How to repeat: Code analysis Suggested fix: S-latch only the first or the last or any random partition.