PQ81144; 5.0.2.1: Filter chain cache leads to
hashmap growth
Downloadable files
Abstract
WebAppFilterManager is caching the FilterChainContents
based on URI, and since each URI is unique, the HashMap of URI to
FilterChainContent can grow without limit.
Download Description
PQ81144 resolves the following problem:
USERS AFFECTED:
WebSphere® Application Server users of WebSphere Portal Server
PROBLEM DESCRIPTION:
Filter chain cache keeps growing if all URIs are unique. It eats up memory
eventually.
RECOMMENDATION:
Filter chain was implemented with hashmap. When URIs are uniquely
generated like those from portal, the cache keeps growing and eventually
causes OutOfMemoryException.
PROBLEM CONCLUSION:
Utilize URLCache to recycle least used entries to maintain cache size
within maximum number of elements.
The maximum number is set to 500, which is big enough for most Web
applications whose URIs can be determined. For applications like WebSphere
Portal Server, which uses unique URIs, the cache size is considered
acceptable, even though the cache itself is not useful.
Filter chain cache may lead to hashmap growth and consume memory. In cases
such as WebSphere Portal Server, where all URLs are unique, the filter
chain cache cannot reclaim memory used by entries, and the cache has no
limitation of growth. This could eventually force the server to shutdown
due to an OutOfMemoryException.
This APAR has been included in service pack 5.0.2.3.
Prerequisites
Please download the UpdateInstaller below to install this fix.