---
title: LRU memory management schemes
description: PingFederate uses an LRU memory manager to reduce memory usage by orphaned data.
component: pingfederate
version: 13.1
page_id: pingfederate:server_clustering_guide:pf_lru_memor_manage_scheme
canonical_url: https://docs.pingidentity.com/pingfederate/13.1/server_clustering_guide/pf_lru_memor_manage_scheme.html
llms_txt: https://docs.pingidentity.com/pingfederate/llms.txt
docs_for_agents: https://developer.pingidentity.com/build-with-ai/docs-for-agents.md
revdate: July 5, 2022
---

# LRU memory management schemes

PingFederate uses an LRU memory manager to reduce memory usage by orphaned data.

During the normal course of transaction processing, the Inter-Request State-Management Service, the IdP Session Registry Service, and the SP Session Registry Service manage memory for PingFederate. End users abandoning web sessions results in orphaned data. To ensure that this orphaned data does not result in excessive memory usage, the data structures used by these services employ a least-recently-used (LRU) algorithm to purge old data. This algorithm automatically removes the oldest entries when a data structure reaches the maximum size.

Configure the maximum size of each data structure in the `<pf_install>/pingfederate/server/default/conf/size-limits.conf` file.