This topic explains how to configure data eviction in VMware GemFire.
Configure a region’s
eviction-attributes settings to keep your region within a specified limit.
Configure data eviction as follows. You do not need to perform these steps in the sequence shown.
Decide whether to evict based on:
eviction-max-memory, where the value that you set is the same for each. If you set different values for these, the value for
local-max-memory will override and replace the
lru-heap-percentage. Eviction continues until the manager calls a halt. GemFire evicts the least recently used entry hosted by the member for the region. See Managing Heap and Off-heap Memory.
Decide what action to take when the limit is reached:
Decide the maximum amount of data to allow in the member for the eviction measurement indicated. This is the maximum for all storage for the region in the member. For partitioned regions, this is the total for all buckets stored in the member for the region, including any secondary buckets used for redundancy. This only applies to entry count and memory LRU eviction algorithms. If heap LRU is used, then the maximum amount of data is defined on server startup as a percentage of total heap, and considers all heap memory usage from all sources, not just an individual region.
Decide whether to program a custom sizer for your region. If you are able to provide such a class, it might be faster than the standard sizing done by GemFire. Your custom class must follow the guidelines for defining custom classes and, additionally, must implement
org.apache.geode.cache.util.ObjectSizer. See Requirements for Using Custom Classes in Data Caching.
Set an LRU memory eviction threshold of 1000 MB. Use a custom class for measuring the size of each object in the region:
gfsh>create region --name=myRegion --type=REPLICATE --eviction-max-memory=1000 \
Create an eviction threshold on a partitioned region with a maximum entry count of 512:
gfsh>create region --name=myRegion --type=PARTITION --eviction-entry-count=512 \
To configure a partitioned region for heap LRU eviction, first configure the resource manager on server startup, then create a region with eviction enabled:
gfsh>start server --name=Server1 --eviction-heap-percentage=80
gfsh>create region --name=myRegion --type=PARTITION --eviction-action=overflow-to-disk