IMap Per Entry Stats Config Option

ℹ️ Since: 4.2

Background

Description

After implementing per config record creation, we managed to break tight coupling between features and record metadata. Based on this, now we have a chance to enable/disable record metadata to reduce memory usage of a record.

Design

We categorize stats in two types: map-level and entry-level. Map level is enabled by default but entry-level is not.

Map-level stats are:

• hits: total hits of map
• lastAccessTime: last access time to map
• lastUpdateTime: last update time of map

Entry-level stats are:

• hits: total hits to entry
• lastAccessTime: last access time to entry
• lastUpdateTime: last update time of entry
• creationTime: creation time of entry
• lastStoredTime: last store time of entry

Replication of Map Level Stats

Map-level stats are created per map's partition. They are replicated to new nodes to be safe from partition ownership changes.

Entry-level stats are already replicated when enabled. No change is needed for them.

Cases That Entry Level Stats Must Be Enabled

• Custom eviction policies
• Entry-views
• For Some Split brain merge policies