[IGNITE-13086] Improve current page replacement mechanism.

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.8.1
• Fix Version/s: 2.9
• Component/s: persistence
• Assignee: Evgeny Stanilovsky
• Reporter: Evgeny Stanilovsky
• Created: 28/May/20 06:48
• Updated: 06/Aug/21 15:23
• Resolved: 14/Jul/20 11:34

Description

Experimentally proven that current page replacement functionality has problems with replace candidate computation. Current implementation obtain 5 random pages and make further decisions basing this pages last touch timestamp and some inner flags, however still possible cases when this pages set can be simply nullified due to inner logic. All improvements need to be proven, for example, by simple scenario:
1. put some data until event EVT_PAGE_REPLACEMENT_STARTED is triggered
2. put 2 times more data than been loaded in p1.
3. execute fullscan (through ScanQuery) for old\cold data processing emulation.
4. start processing only pages which can fit into current mem region.
5. measure "replacedPages" metric.
(i attach code mention above)

Issue Links

• is related to: IGNITE-8299 Optimize allocations and CPU consumption in active page replacement scenario
• links to: GitHub Pull Request #7864
• links to: GitHub Pull Request #7919